After giving the matter some thought I have come up with two more mysteries, an inner and an outer one.
Vulcan's knowledge (minor house mystery)
Ease Factor 15
The magus is closely linked with all devices that he manufactures - whether the item is for himself or for another he is able to use his link to make more powerful enchantments. The magus hubris score is added to all lab-totals involving creating the item - however he must have opened the item himself and been the only person to invest powers into it. This virtue only applies when the magus is in charge of the lab activity.
initiation script +11
The magus must locate a blacksmiths anvil that has been used only for mundane work for 15 years in a place without any realm auras. (+3) He must transport the anvil by hand-cart using only his physical strength to Mt Vesuvius (+3) where he uses it for a season to craft a sword. (+1)
The magus must battle a magical creature whilst wielding the sword in their hand. (+3)
The magus then lies down on the ground, with the creatures body on their chest, and the sword is plunged through it into their heart.
If the magus has succeeded the sword and body will vanish becoming one with their gift. (+1)
The magus gains a greater link with their magic items.
Vulcan's Hands (major house mystery)
Ease Factor 21
The magus can handle multiple identical items at the same as if they were a single object. The items must all be identical, and when opened they are marked with the verditius rune for "Eternity" at a cost of a pawn of vim each. This adds 5 levels to all effects the devices contain. The magus can operate on one item per full point of Hubris (limited by his lab-total and the amount of vis he can handle in a season).
When opening the items, the magus spends the season opening them all at the same time, crafting the rune onto them and binding them together. The items become permanent Arcane Connections to each other.
When enchantint the items, the magus calculates the total needed as normal for the effect they wish to imbue (including the extra 5 levels for the rune). They then add 5 levels per additional item they are imbuing.
This becomes the lab-total for the combined work. The enchantment process is the same as normal for lesser and greater devices.
Once the process is finished, and the items are to become unique, the ceremony of seperation must be carried out. Compare the magus Perdo Vim + stress die lab-total to 10 + the combined number of pawns the devices hold. If it is greater than or equal to the number the items become unique. If it is less the items remain permanent Arcane Connections to each other, and cannot be seperated again. If you botch, he receives a number of Warping Points equal to the total number of pawns of vis in the item.
The items do not all have to be given the same enchantments - for example a particular enchantment could be invested into only one of them.
initiation script (+13)
The innitiate creates and opens as many small hammers as they can in a single season. (+1)
They then lie down before a forge of Hephaestus, at midnight on the eve of Hephaistia, remaining naked, defenceless and silent throughout the night. (+3)
The mystagogue will select one of the initiates healthy legs, and all throughout the next day, from sunrise to sunset the mystagogue, starting each hour they will strike the leg with each hammer in-turn, healing it with magic before breaking it again. When the sun sets and the magics wear off, the hammers are then sacrficed the forge as the initiate passes out. (+3)
When the initiate awakens, they will have gained the gift of Vulcan's hands, but their leg will never be whole again. It is permanently lame, if their other leg is also damaged they are now crippled. (+3)
Due to the hammers being linked to them whilst symbolically destroyed the innitiate loses the minor virtue Vulcan's Touch (+3)
Example Vulcan's Hands
Mathius has a Magic Theory of 10, a Philosophae of 5, a Hubris of 6. He knows Verditius Elder Runes, Vulcan's knowledge and Vulcan's Hands
He has been comissioned to produce 2 identical swords, as greater devices, and instil in them the effect "Leap of Homecoming", R:T, D:M, T:I to send the wielder back to a set place. He was provided with two Arcane Connections, 30 pawns of Vim and 8 pawns of Rego vis.
As he desired a sword of his own, he decides to open a 3rd sword at the same time to save himself a season.
He spends a season crafting 3 identical swords with his forge, and carves the rune for eternity onto each of them. As the season draws to a close he uses 45 pawns of vim to open them all, and spends 3 pawns to empower the runes.
He put's his sword aside and begins to enchant the other two swords with the desired effect
The Leap of Homecoming base 35, T:Touch (+1) = 40
+5 levels for the Eternity Rune
+5 level for enchanting a second item
Final level = 50, vis needed is 10 pawns (5 pawns per item)
He has a Rego Corpus lab-total of 76, meaning that he can enchant the effect in two seasons.
He then prepares the ceremony of seperation on the 3 swords, He needs a perdo-vim + stress die lab-total of at least 45 to seperate the items, which he passes easily.
He then returns the two items to his client and charges another 60 pawns of Vim and 16 pawns of Rego.
He has saved 3 seasons of his time time (2 seasons of opening and 1 season of enchanting) for the cost of 3 pawns of vim and 2 pawns of Rego. He quietly laughs to himself as his client expresses his admiration at the speedy delivery.