Nah - if you built it legally, you built it. Past tense, done deal, you're good to go.
Later penalties and changes shouldn't affect what the mage achieved in the lab previously.
(And it'll take more than that to get me on a tangent about Berklist, at least.) 
Here Erik is hitting it...right on the head as it were...
Create an item...Fill the capacity of the item (number really doesn't matter..but you used Elder Runes)
Make it your Talisman...
-Now, as per the rules you could expand it to your highest tech and form...but you can't come close to that because of the E.R multiplier...
You MT goes up.
You now add a material to the item (say a gem) using Greater Talisman...
-Your total ability to create using E.R. has increased enough to encompass the gems added capacity..so the object is within the Size/Material constraints...it is also within the MT restraint due to number of materials...
It seems a little much, that a character that has sacrificed so much time and effort to gaining the Mystery (not to mention the E.R. mystery, and in this case the Reforging Mystery), would NOT be able to add that additional capacity to the Talisman...
(For the record Erik, I am with you on the doubling ability opinion, but I like magical devices, where your opinion on them is well documented.. 
-which is where I was going months ago when I told you I would eventually post the Talisman...when it was done ) 
This is an exorcist in what a Good Verdi could do given the 'stuff' to do it with...Why are Verdi Talismans so desirable? This will answer that question...
As for the quantity of Vis used...if someone would like to discuss THAT, start another thread...
As for how much a character can save up, that depends on the character of course, but a good SG should never penalize a character for working hard and accomplishing his goals...
As for Eriks point of making characters that are that accomplished 'Work for' (or something like that)...
Background...
The character is dealing with ('several' years)...
The Church trying to hang/burn etc his son because his father is a 'witch' and obviously deals with demons...(Almost had to take out an Army to get his son back...whew)
King of Scotland and his army are sitting in the Main Covenant building, sucking up food and drink with facility (ouch that hurts the wallet), Asking him why so many villages have been destroy around the area......There are several Magi (rogues, non Hermetics etc..) turning loose their critters on the locals...Working on that right now...
The local town that was destroyed, moved in and destroy our peaceful community of hedge Christians, and brought their priest...and aura...
We have a Hydra like creature living in the (Regio) main Covenant building..it can only be killed by certain step by step, ah, events...
The Tytalus Blew up his tower...(We think he is in twilight...Facing various charges IF he returns...(being Diedne is one)...
The Faeries destroyed the rest...
(rebuilt now)
The Covenant has a Feud going on with a Covenant in Ireland over some Vis
We managed to stop the magical 'dog thing' from eating our Vis rabbits (plus other sources)....
Add to that all his LAB work, Research, and search for Ancient magic...been a little busy...
So the character acquired the greater talisman mystery after they already had a talisman that was opened for greater than their talisman limit by using the elder runes virtue? In that [articular case it would be cruel to the point of silliness to abide by the rules as written in this situation and not allow the character to gain some benefit from their initiation rather than twisting things so that the player can have some fun with their character's new virtue.
You've clearly got lots to do when you sit down at the table with your players and it might be a determent to your game to spend time telling stories about how the Verditious goes through yet one more initiation. When I first posted the message that you're responding to I had included the exception that if you've got other stories to tell sweep the issue under the rug and get moving with the things that are going to make your game better. I edited this exception out of my post and here is my thought process so you can understand why I wrote what I did;
The magus who runs into this problem is a magus who has nearly filled up the capacity of an item that was opened with a whole lot of vis I'm guessing that this means more than 60 pawns, possibly much more.
That means that the character has probably invested over 600 levels of effects (possibly lots more). How long does this take out of the character's life? A decade? More? That's just in investing effects. How many attunements must it have ten? more?
That character's talisman has been the focus of years and years of the character's life, and now they want to change it in ways that don't fit the system. To repeat: the character has decades of work invested in that talisman, the character wants to have his talisman exceed normal hermetic limits.
So: How do you decide not to make a story out of that? I'm just thinking if a character wanted to achieve immortality in a game I was running I'd make a story out of it, if a character wanted to topple the the Danish monarchy I'd make a story out of it and if a character wanted to elevate their talisman beyond the even the bounds of the greater talisman virtue I'd make a story of that too. To quote from Mysteries revised p13 "progress in a Mystery Cult depicts an increase in power with more gain than loss, and no fixed ratio. Indeed the greatest 'currency' transacted is the 'story' in which character activities reward the the storyguide and in turn the player's character".
Yet by the same token, if you're not focusing stories around the talisman why are you giving it extraordinary power?
Somehow voicing an opinion that talismans are important devices for their creators and only dumped to the side to be replaced by the new shininess has convinced you that I hate magic items. I'm the fellow who tried (or is trying but my players are all taking an extended break?) to run a game entirely about the advancement system. I'm not certain which of my posts gave you this impression but the impression is in error.
You've mentioned that you perceived my dislike regarding these topics before. I didn't respond then because it wasn't a big deal (and it still isn't) but really you should know that I'm quite fond of the magic item creation rules. I think that talismans are incredibly cool and they've added a great deal to my game. Furthermore I think that the Verditious elder runes virtue only does more harm than good to a game when it is used by certain specific sorts of characters (when run by certain specific sorts of players).
I disagree. The Elder Runes add depth of potential and back-story. Recal how lame Verditius runes from earlier editions were. The expanded vis use is not an issue for me, because I was so used to the Vim + Magic Theory formula. 2 x Magic Theory seems too small for even non-Verdi magi.
As for the true power of the runes, adding the corresponding Art twice, well that's what makes them so cool! Mind you, that this adds +5/+10 to the level of each and every subsequent enchantment, no matter what, whether it matches the runes or not. +10, no big deal, right? After 10 Investments, that's 100 levels of space used up. An item made without Runes and higher Art scores instead is going to be much more powerful.
Here is my question. Does the engraving of permenant inscriptions count as a Craft ability? Craft-Engraver? Craft-Inscriptions?
Nothing I said is in conflict with anything you said even a little bit. I don't see any disagreement.
It wasn't intended as snark. I think that elder runes can, more than most other virtues, be a pain when weilded by the wrong player. Is that so snarky?
No, not on me, your cool with me so far. I meant towards whomever this troublesome player is. I might be reading onto something and I am mispercieving it, so it's not a big deal. But anyway, the only wrong player is the one who doesn't show up for the game 
More importantly, I do not understand your assertion that Elder Runes can be a pain in the first place, let alone a greater pain. The rules work and mesh well. The only thing I can possibly concieve your having a problem with, and correct me if I am wrong, I think that you may believe that their use is too powerful.
If that is your issue, then we will gracefully have to agree to disagree. I like to play with power, as PC, NPC, SG, GM, DM, or whatever. Power isn't bad, it taking it for granted that's bad. Heck, even then, all's good as long as everyone has continued fun.
However, if your issue is some mathematical or mechanical fault within the ER rules, please inform me because I may be unaware of it. Mind you, I do not have TMRE, so if the Greater Talisman Virtue combined with ER is the actual probblem, then I won't quite understand yet.
This doesn't happen all that often (especially when it comes to ordering Chinese food), but I'm about to agree with Urien. I tend to let characters get away with things if they spend time on it. Despite the wording of the rules in the main book I would allow a Verdi that spent the time and whatnot on getting Elder Runes added bonus to his talisman. All it means is spending even MORE time getting the vis, opening his talisman and enchanting more effects into it. It's not like they just drop into the local shopping mart, get the virtue and run out and make a kick-ass talisman the next week. If that's the driving force behind their character then why not let them do it, it's not about to ruin the game because they have a couple more powers in their talisman instead of spread over two items.
And your curry chicken smells the place up Urien.
And you're ugly!
Ditto. Effort and good actions should get a reward. They do IMS.
Xavi