Unique ID separate to the Name applied to each character - visible on death
A feature of some other online games like RUST is that players will have a unique ID bound to the account (character). This extends further to a unique body that cant be changed. When you change your name you can fool some people that you are someone else, but others can tell by the look of you or your ID if they combat you.
What I would suggest for Helbreath is that each character has a unique ID, that can be inspected - perhaps only when the player has been killed or is pretend corpse.
This will help to track spies, if players are known to have repeatedly violated community rules around town behaviour - they could always be found by their ID.
If they do enough bad things like DS or scamming - they would have to delete the character and create a new one to fully hide from their crimes. Changing name will trick some, but guilds would be able to know to not let them in.
I’d prefer to see a unique ID per account, not character. It could be something like you type:
/whois Jess
This would produce a Unique Account ID, (not the one used for login).