Gotcha. Revising.
I'm still thinking the affinity Creo through. My thinking is an Affinity (Art) that reinforces the underlying magical crafter theme. I may go with Affinity (Rego). Open to advice.
I'll pull out Ambitious and hunt for an appropriate non-story, non-personality flaw. 
Draft v1 Character Sheet: Argentius ex Verditius at Gauntlet
(I've tried to model character worksheet on a couple flavors I saw around the forums as well as what I learned building Bartomeus.)
I'm very open to suggestions and advice at this point on characteristics, abilities, or arts. The parens' approach to training is to establish a broad foundation upon which the new journeyman can build rather than specializing at the apprentice stage of development. Holler if this is a bad ArM strategy.
Updated Background Notes with Timeline
Argentius ex Verditius, an ambitious and arrogant magus, is determined to re-discover the inner mysteries that led to the creation of the fabled Rings of Verditius under the tutelage of Wayland Smith.
1156: Birth
Parentage: The offspring of a Sidhe dalliance between a Sidhe father (not a high noble) with a daughter of the notable (possibly noble) Colagera family of the Kingdom of Candia (Crete). The Sidhe father takes the boy child to Faerie.
1156 - 1161: Childhood
Raised in early childhood in his faerie father's household, fostered to a dwarf smith working in the household. The relationship sparked his initial interest in crafting items of beauty and utility.
11561-1166: Grammar School
Sold by his father to an arche of the Theban Tribunal Treasury Council assigned to find Gifted children, Argentius is educated alongside several other Gifted children in a covenant Grammar School until the next gathering of the Tribunal 5 years later at age 10.
1166 - 1181: Apprenticeship
Presented for apprenticeship at the Tribunal meeting on the floating island of Delos, Argentius rises as a top prospect among the 14 apprentices interviewed at that year's tribunal. He is favored highly enough that he has gained the second highest number of tokens in his cohort. His interview with the successful and arrogant Eusebius ex Verditius appealed to his budding ambition and boyish interest in magical creation and enchanted items. At the Apprentice Presentation, young Argentius chose to apprentice under Eusebius, a decision driven by both the number of tokens received from the Verditius magus but also the prestige and future he was confident could come from Eusebius.
1166: Initiation into the Outer Mystery of Verditius Magic
1180: The Contest
During the Contest year of 1180, Eusebius took Argentius to The Contest of House Verditius and entered him into the apprentice category. At fourteen years into his apprenticeship, Argentius had developed enough skill to craft a particularly innovative ring. Eusebiuis did not enter his apprentice into the Contest to simply help highlight the young man's work. Eusebius was orchestrating an offensive move in his vendetta against a rival, who his network of spies had informed him was also planning to enter an apprentice into the contest. Eusebius's move succeeded (forcing a delay in the rival's arrival, disqualifying the rival apprentice's entry). When the sigils were counted in the apprentice category, Argentius had won.
Ambitious and thirsty for knowledge, Argentius asked a boon of the Primus: in lieu of choosing his prize from among the Contest entries, Argentius asked to be initiated into the Inner House Mystery: Verditius Elder Runes. Argentius knew the legends of how this inner mystery was said to have been taught to Verditius the Founder by Wayland Smith, and the young apprentice was hopeful that this Inner Mystery could set him on the path to recovering or re-discovering the lost knowledge of creating rings of such legendary power and quality.
The boon was granted.
1180 (Winter): Eusebius, acting as Mystagogue, initiates Argentius into the Inner Mystery: Verditius Elder Runes.
1181: Gauntlet
Fascinated by the legend of the rings of Verditius and trained by a master jeweler, Argentius pours all he has learned into investing a lesser enchantment into a beautiful, yet simple silver ring. (Lesser Enchantment TBD once Arts and Abilities are locked in.) Eusebius accepts the "masterpiece," and Argentius steps forward as a new journeyman of House Verditius, determined to rediscover the inner mysteries of the making of rings of great power. Age: 25.
Additional Background:
Description: Because of his strong faerie (Sidhe) blood, Argentius is uncommonly handsome and attractive. Argentius has a lean, willowy build, long in limb and narrow in frame though not frail. His silvery blond hair is kept long though most often tied or braided into a tail that hangs down his neck. He has unusual, dark violet eyes, beautiful yet arresting in the intensity.
Vendetta: Argentius's affiliation to his parens is strong, grown so in part because of the absence of a connection to a biological father figure and in part because of how Eusebius drives Argentius to reach further in his work. To assure that his promising young apprentice doesn't simply become a rival, Eusebius cultivates this close relationship because he believes it will serve his own ends and neutralize a future rival. Thus Argentius becomes connected to and ultimately joins the vendetta of his parens. (Note: if we go down the Contest path, I could see how that is a strategic move where the parens moves Argentius into position to block his vendetta rival's own apprentice's entry into the Contest.)
Verdituous elder runes do count against your starting virtues.
OK. Are they considered a minor or major virtue?
Also, would you be open to adding a Sympathy Trait? Was reading in the Faerie book and thought it might be consistent with the character concept.
Verditius elder runes area minor virtue
I am fine with sympathy traits, but those do involve more virtues and flaws.
According to RoP:F, having Strong Faerie Blood allows one to have a Sympathy Trait of up to +3.
Not exactly
It raises the limit on a faerie sympathy by 3, but it does not by itself grant you the sympathy.
So with warping 0 and a faerie sympathy it could be up to a +3 (+4 or +6 in some cases), and if your faerie warping goes up to 1 then the sympathy limit likewise rises.
Ok. I'll drop the Affinity with Rego, replaced by the Verditius Elder Runes.
Reading more on Sympathies.
Okay, we will need spells, I should get a sheet up for this character soon
Ok.
With your approval I would like to add Nobility +3 as a faerie sympathy.
Hubris: As I review the Hubris section in HoH: MC (118-12), I'm coming up with a Hubris score of 4 at Gauntlet: 3 for Major Flaw Pride + 1 from the Hubris Minor Flaw itself. From there it looks like an XP process as with an ability development. Argentius would have 2 XP at Gauntlet: 1 for winning the apprentice contest and 1 for learning a minor inner mystery per the chart on p 120. As I read the guidance, it would be 73 more xp to move the Hubris score up to 5. Do I have that right?
I'm also reviewing the arts scores. I think I've pushed too much toward a generalist, so as I look through spells, I'll also do one more pass at the Arts configuration.
Very well on the arts configuration.
Regarding adding Noble as a +3 sympathy- this would either be a major virtue or a minor virtue and 25 experience. It is explicitly not something you get for free with faerie blood or strong faerie blood.
I see it now in RoP: Faeries. Now I understand. I'll put it on the "wish list" for another time or however the story develops.
Quick Arts Question:
If there is no score in an art, is it still assumed to be "opened" with a score of 0? So that If a magus, for example, had Rego at 5 and Aurum 0, they could, theoretically, still learn and cast a Level 10 Ward Against Rain ReAu spell.
Or does there need to be at least a 1 in the art?
it is at zero when opened, and can be used from that default,
Ok, I think I'm there assuming no oversights, typos, or other errors. I could spend another week looking at it, but I think it's good enough in the spirit of "done is better than perfect."
Argentius Ex Verditius at Gauntlet
I've included spells on the second worksheet (with some possible future spells listed lower on the page).
Please let me know if you would like an additional write-up on goals and motivation beyond what I've written in the background notes.
Thanks for all your advice and help! (All of you!)
ps. And your patience.
I'm working on educating myself more on the details, limits, benefits, etc. of enchanting, especially for Argentius in particular.
A question: on p. 128 of HoH:MC it talks about a second application of the Elder Verditius Rune Inner Mystery and how it allows the magus to use more vis in his enchanting in a season. It becomes Philosophiae times Magic Theory. Does that apply even if an elder rune isn't be inscribed into the item?
I'm going to say yes, but that is essentially a house rule to cover the ambiguity.
I also want to confirm my understanding of the statement: "forge items from
raw materials as part of the process of enchantment" (ArM 5e, p 93).
In the case of a ring, Argentius could use his craft to forge the ring in the season he opens the item for enchantment. He could also inscribe up to 2 elder runes on it, taking on the requisite levels to the effect and vis cost.
If Argentius were making a wand made of yew wood, he could forge the raw wood into a wand of his design (say curved grip narrowing to a blunt tip). He doesn't have a wood working craft, but that would be ok per the rule above.
Do I have that right?
As long as he is enchanting the object in some way (opening it, investing effects, etc.) yes.
If you have a moment, I'd like to put out some possible enchanted items as test runs of my understanding of enchanting.
Lesser Enchantment
Ring of the Porter
MuTe 10
Lesser Enchantment
Lab Total: 38
Tech: Mu 6
Form: Te 10 (5 * 2 Minor Magical Focus)
Int: 3
MT: 5 (puissant)
Aura: 5
Craft Jewelry: 6
Inventive Genius: 3
Effect Level: 18
10 Spell level
+3 6 uses per day
+5 maintains concentration
Effect: As per spell Unseen Porter
Vis Cost: 2 pawns
Completed in one season.
I think I may have missed a lab bonus because Argentius knows that spell.
Am I on the right track for a lesser enchantment given Argentius's particular skills?