Many bosses offer unique weapons if killed a certain way. This Remnant: From The Ashes Alternative Boss Kill Guide lists each of the bosses with a discovered alternative kill method so you can get both the normal item drop and the advance item drop for the alt kill.

Whenever you defeat a boss in Remnant, you get an item to craft either a mod or weapon. This is just a normal kill, dealing damage until the boss dies. However, certain bosses have hidden items that you can obtain by defeating the enemy in a certain way. Below is a list of the different bosses with alt kill methods and how its done.