Hello !

I'll answer from a French point of view, geographically. That is, I purposely leave alone Italian peninsula, that was a bit more evolved on these concerns.

First of all, it is important to understand how banks worked, what their purpose was and how they were used.

First answer is, they were nearly non-existing to commoners. Most of the population didn't have access (or did not need it) to the banks. They were paid in coins, were paying with coins and their money never reached the safes of banks. It did not need to. Their hoarding of money was more in the "keep it hidden under the bed" fashion, when they could afford to spare some money in the first place.

That leave us with two kind of people : wealthy bourgeois and merchants, and nobles.

Now what did they use it for ?

The first use of banks was for loans.

The second use was in the form of "lettres de change", "bons au porteur". They are the first prototype of modern checks. They were generally of two forms :

- Bons au porteur (literally : voucher for the bearer) : a piece of paper saying "give that amount of money to the man that will present you this voucher. It shall be taken from my money" with the signing of the merchant emitting it. It was very practical in the way tat it avoided people to carry large amounts of money on long distances.

- It then evolved with the mention of the person that could use it. "Give that amount of money to Sir Example of Generic, it shall be taken from my money", again with the signing of the merchant emitting it.

What were the respective benefits and drawbacks of those two forms ?

Well first of all, they were both very practical in order to carry large amount of money. The bons au porteur could also be given to someone else in payment of a debt, just like money. The second kind were safer : bandits could rob you, but the could do nothing with those : they could not prove they were you.

Now we come to the part that interest you most. How did people identified themselves when dealing with banks ?

Generally, through heraldry, seals, rings. The heraldry of a knight was known, meaning that you could check, if you wanted, that the knight in front of you really is Sir Example of Generic, and not Sir Bandit of Sneaking. Bankers generally did not, however. They did not have to. Honor and word were very important thing at that time, and a knight who lied about his identity would soon be discovered and be looked upon with contempt and disdain by his peers (plus justice problems, of course).

Same goes for seals, which are considered a solid proof of the quality and name of its bearer.

Please notice that this way of doing things may also apply to regular payment. For instance, a nobleman could go to an inn and say he would pay later. Of course, the owners were not forced to accept, but when the noble was living nearby and was known, that was no problem. They knew they would be paid eventually and that their guest was not carrying all his money with him everywhere he was going.

Nevertheless, that was not totally safe. You can find examples of people arrested, judged and (generally) put to death for usurping the identity of a nobleman. Usurping one's heraldry was considered a terrible crime (and as you can see, for good reasons).

I hope that answer your questions and I'll try to be ready for additional commentary or follow-up questions :)