Someone brought up the Chrestomanci books by Dianna Wynne Jones as an example of a Restriction. The titular Chrestomanci cannot use magic when touching silver or carrying any about his person (eg coinage).
But for a Magus in Mythic Europe, we wonder, how often would a Restriction like that come into play?
Are there any magical operations that need silver involved? Would a magus normally carry silver coins?
Considering that because of the gift, magi are not frequently in contact with mundane, it limits the need to have coins with them. When they trade with other mages, silver is rarely the currency. And unless living by themselves, all their daily needs will be provided by the covenant.
So the occasion for them to have coins can be very limited or even completely avoided.
If their restriction drops as soon as they are no more in contact with silver or don't carry it with them, it is relatively easy to mitigate. If it takes them severaly days without contact with silver to be able to perfom magic, then it requires a bit more organisation from the mage.
As you can see, the standard answer is "it depends". A Mercere magus doing one season a year on the road is more likely to be affected by this flaw. A Jerbiton settled in a city will be severly hampered by such a limitation. But a Verditius trading in magical item won't be as much affected despite his business: he is more likely to trade in virtus/tome/gold and he can rely on magical item to perform his magic and when dealing with mundane will act through Venditores and won't handle the silver himself. And a Bjornaer won't care since he can rarely carry much in his heart-beast anyway.
It also depends on where you are. In Italy you can probably simply use letters of credit. Eastern Europe gold is the more common currency, Western tends to use silver, though in either case you can carry gold and copper if you have to carry your own funds. Of course keeping silver in a chest, saddlebags, or otherwise off your person is always an option as well.
While I agree with Ezechiel this is a bit a situational, I can add two points:
Most paupers don't even dream in seeing a silver coin but most less nobles, knights, merchants and specialiss can carry silver coins and wear silver jewerly, silver crucifixes can be really common.
Example: A noble marriage, most guest can be wearing or carrying silver.
Faeries dislikes iron and that make them replace it by silver in armour and weaponry.
Example: Dealing with Queen of Winter (polar-bears-in-silver-armour) Honor Guard can cause some trouble.