Then Red spell wand, wand of might or items alike weren't always inside a bag? I'm sorry but my memory seems a bit biased lol.
I think they were not. In cip files there's "wand" flag which makes wands go to a bag, but it was made for those of version >= 7.6. I assume this flag didn't exist before.
Weapons (melee weapons, bows, crossbows, throwables, 7.6 wands), shields and items that expire or wearout - this stuff went to a bag.
There was also a bug, or rather an oversight, which caused these types of items that were also cumulative generate only in number of 1, regardless of what was set in the loot. It went unnoticed because the only cumulative things among these are throwables. E.g. goblins always dropped 1 small stone, orc warlords dropped 1 throwing star etc., even though in their loot there were up to 3 stones and up to 40 stars.
There was also one more oversight, which I didn't mention in that long post about loot. Rings, legs and amulets are treated differently in the function that creates item at creature (they put a wrong slot number in the equation or something, I don't remember exactly) - instead of going to their corresponding spot first, they go to hand slot, then the other hand, then arrow slot, and then the right slot. This can be noticed in giant spiders loot: when there are 3 stacks of gold and brass legs, 2 stacks and legs will be in the body, while the third stack of gold in a bag. Brass legs also don't add the arm, because they are in hand. It only happens if legs are generated before gold, so in the same case knight legs would be in legs slot, because they are after the gold in the loot, unlike brass legs. If it was 3 stacks + armor or helmet, it would be all in a body, no matter what.
That behavior can also be noticed when buying stuff from NPC, if you buy an armor it will appear in your armor slot (ofc unless it's taken) but when you buy legs, they will appear in your hand.