To apply as a mercenary you should see the army on map. I don't wanna fight for Sargoth when i am in Shariz. Additional suggestion to this, make non clan mercenaries' name something standart -like "(faction_name)_merc_(number)".
This is actually a really interesting idea, I think. So if a battle is fought, neither side can see who has signed for the other side (on the battle list) - just how many. It would mean more chances for intrigue and backstabbing allies or tactical stuff.
And then in the actual battle their identities can be secret, as Sultan Eren said - just (random example) Fallen_Mercenary_1. The whole idea is that players are representing random mercenaries anyway, isn't it?
Though I don't know if that would be possible. It'd be interesting - for example a secret Merc contract would actually be secret this way. Of course the hiring faction would have to be able to see the real names in order to pay accordingly and hire the right people.
And for those who want to see their K/D, it would show up in the battle history like it did before.
So the faction fighting would have their names revealed, while mercenaries from outside their faction wouldn't. Maybe make it optional for allies who want to demonstrate their loyalty, and for others who want to improve their reputation as a mercenary.
I think this is a really good idea