Now that the equipment in cRPG has changed quite a bit, I'd really like to see this, and I think it feasible. I'm just not quite sure on the proper implementation. Basically, a merc in a strategus battle should have to bring their own equipment to battle. This will make mercs more unique and valuable and help people get a reputation. Maybe you can count on one guy as a great heavy cavalryman, so you are willing to pay him lots of gold. Another might be a skilled 2 hander or archer that you can count on. Of course, this would mean you'd need to pay them a lot more gold. But you wouldn't have to purchase as much equipment for the battle.
IMO this has several benefits, in addition to making mercs more unique and not just another number. For example:
It makes things more realistic and fun, I hope at least. I know I'd like it.
It will make mercs more cautious in battle, since their equipment is there own.
Groups/clans will get more recognition, and they will be able to use their own "uniform" and use their own tactics as a squad.
Mercs will bring more variation in the equipment and weapons seen on the battlefield, and may lead to some maneuvers that take the enemy team off-guard.
Now, how to do this exactly, I'm not really sure. Maybe the easiest way is to make it just like a cRPG battle; you bring your own junk, and it can break and need repairs. Alternatively, have players buy their own stuff on strategus and use that equipment, not their cRPG stuff.