I'm thinking about a special run:

I don't have my own weapon (except right at the start of the game), but always have to use the weapon looted from an enemy for the next one.

This means I have to train to Master not just one weapon category, but two, Pistol, and Rifle, and probably have to train Low-Tech to Advanced. Since this doesn't leave much left for Computer, collecting explosives for eventually destroying robots that can't be remote-controlled, or in the case of me lacking an explosive-capable gun, needs to be allowed.

In the case of killed MIB/WIB, the weapon used to kill them needs to be used again for the next enemy.

In the case of enemy teams, I wonder if the rule is always applicable, since the remaining enemies need to be lured away from a body, and I'm not sure that it's always possible to distract them so that they all don't see me crouching towards the body (before I have Cloak). This means it could be allowed to use one and the same weapon for all enemy team members, and pick up the weapon from the enemy neutralized last.

In the case of an enemy killed by a reprogrammed turret (e.g. at the Statue entry in the beginning), that body has to be looted according to the top rule.

Did I miss something, are there other situations/conditions that need ruling?

Edit:
I may use weapon upgrades, even multiple. The upgraded weapon has to be dropped after the kill(s) just as every other weapon.