When learning about battles I often hear alot about the setting, preparation, engagement/tactics and results of said battle. What I don't know much about is the condition of the battlefield after the result. Take Cannae for example, I can assume after the rout of the Romans there were tens of thousands of bodies all over the place. And given the limited lethality of stab wounds is it safe to say the many of those on the battlefield were not actually dead but just wounded and/or the process of bleeding out slowly? What did the Carthriginians do with all the bodies? Was there ever a post-battle edicate of tending to wounded men from the losing side, or respecting burial rites? Or did the victors just patrol around skewering the dying and looting? Was there an advantage to pretending to be dead so that when the enemy army leaves you have a chance to escape?
Looting. So much looting.
It'll come as no surprise that armor and weaponry are expensive, and that's not counting what trinkets or knick-knacks there are that some of the wealthier soldiers might be carrying. Since pay was likely to be poor to nonexistent, plunder and booty were the natural ways for soldiers since time immemorial to make a few coins, and if that meant stripping valuable lorica or chainmail off the guy you killed, so be it. (And if the guy turned out to be not quite dead, he could be seized, enslaved, and sold off, assuming he survived the wound. That was the usual fate of POWs in the ancient world. High-ranking prisoners might be treated better, too, especially if they might fetch a ransom.)
This didn't always happen after the battle, strictly speaking, either. Battle after battle sees reports of undisciplined troops break ranks and plunder, only to be hit by a regrouped enemy. Portions of the Iliad features fights over a fallen warrior's armor; since these are invariably heroes with their own followers, the fights often see the followers try to recover his body and his gear to give him an honorable burial or cremation, and his opponents try to claim his armor as a prize.
That's with a more personalist, individual style of combat, though. More organized phalanxes and legions had more systematic rules about plunder--namely, that it belonged to the army as a whole, and that you had a responsibility to turn what you've looted in to the army, and you will have your share of the overall loot later. This was an ideal rather than a reality, and it's impossible to know how much in the way of moveables disappeared under individual soldiers' cloaks, but in all cases, the process of picking the battlefield clean would've started early and been very thorough, whether officially sanctioned or not. (In that way, modern RPGs with an emphasis on killing enemies for their loot can be oddly historically accurate--with the big difference that the PC(s) would be in a competition with other scavengers to try to find the best stuff.)