Every monster in the game drops items when killed however they drop depends in the difference between the monster level and the killer level. Dwarves have a skill (Spoil / Sweep) to get more items from monsters than usual. A very common drop is adena (currency in game), the amount dropped differs slightly, but not much.
Kinds of drop[]
As said before, adena can be dropped, but also armor, weapons, crafting materials and other things. Usually the drop exists out of adena and some crafting materials, there is a slight chance that armor or weapons will be dropped.
Also, every monster has a extremely small chance of dropping one of the two demonic swords, but there are rules about the demonic weapons, just one of each can exist at the same time in the world.