[Lava]

Gnoll Bruiser kit disadvantages...

First item shows "May only allocate proficiency slots in the following weapons: Halberds, Bastard Swords, and Axes." 
Second item shows "May not allocate any proficiency slots in the Single-Weapon and Two-Weapon styles."

I think me and TheArtisan (who worked on the kit) were testing Axes at some point, we didn't manage to make it work fine and not... awkward. Will check that along with other things when I get to updating this mod.

I understand that this is due to limitations from the game engine; are halberds and large swords the only weapons that Gnolls have animations for? Do they have the necessary animations for a sling?

Sadly, yes. You will see that all in-game gnolls attack with halberds and swords (actually short swords, I think? But I made sure his sword simply uses shortsword animation rather than long sword animation). There is no sling animation but it doesn't bug too much, however it will not show the weapon animation anywhere and it may look a bit as if he was throwing those stones rather than they were shot from a sling. But it was that or leaving him without any ranged weapon.