i free a stormcloak prisoner from imperials and got a 1000 bounty, the nord ran off this save that i actually got him weapons to use... instead of engageing in the fight he ran off, so now i dont have final witness eliminated, and he didnt assist me in combat... kind of.. bothersome..

That Nord didn't want to help you.

The prisoners never stick around to help you.

did you attack the Wimperials first or remove the prisoners binds first.
removing the prisoners binds causes the wimperials to attack you and you get no bounty.

they help you fight if you share items with the prisoner before releasing them. but after that he runs off, to windhelm and ulfric, like a little girl

You must free the prisoner by talking to them and selecting the correct option. You can either decline to free them, just free them, or free them and share your items. They will help you in the battle, and you won't get a bounty.

the first 4 attempts he engaged in the fight after i freed him without sharing and with sharing... but all i could give him was a bow...

the time i actually engaged and successfully killed, the same way i had approached all other scenarios, i got him a sword to be up close in the battle...

instead he ran off. I think i had been engaging in combat first, but the point being the timee i actually had hima sword, he didnt stick in fight

fists and bow he would.

This must have changed then in a patch. Each time I gave a prisoner anything they just ran off.

Even if they are going to help me a battle, I am not giving them a weapon to take from me after it is over, which is the other reason why I stopped equipping the prisoners.

Good move he probably ran off to become a bandit.

If you accidentally hit the prisoner during combat, you may get a bounty, which is why I either just let the Imperials kill him or do my best to just avoid friendly fire.

As mentioned, make sure you first speak to the prisoner and choose to free them, rather than begin by attacking the Imperials. There should be no need to worry about a bounty and eliminating witnesses, as anytime combat is initiated by the opposition and not the player, there will be no bounty received as then it's "self defense" because they started it.