The downright shoddy tactic employed in games like Call of Duty rears its head where you have to contend with dozens of respawning enemies in one area. (gameondaily.com)
In order to retrieve it you'll have to make your way back to where you died all while dealing with respawned enemies. (cogconnected.com)
The game doles out enemies at it's own pace, only respawning enemies in an area after certain plot points, so if you aren't particularly good at keeping up with the skills you need to farm upgrade pieces, you can end up underpowered without much you can do about it other than persevere and try harder. (the-gamers-lounge.com)