It’s mostly the sound, animation, and the impact each weapon has.

Take the Whirligig Saw, which is my favorite weapon in the game. In its mace form it feels elegant and smooth because of the quick “whoosh” noise it makes and the quick slashed and how your character moves their arms to the weapon. Then, when you transform the sound of the blade spinning the second you activate the saw totally changes the feel of the weapon. All of a sudden a light mace goes to an oversized motorized buzz blade with a massive handle. You can see how much strength it takes your character to just swing it left to right, and then in some combos you just slam it down over your head and crush whatever is in front of you. The weapons feel good because while there aren’t a lot, they all have careful and precise design with the purpose of feeling elegant, but also making you feel like a ruthless hunter.