Note that all extra accessory slots in AvalonMod for 1.2+ versions are removed. This is due to balancing purposes. In other words, this feature is out of date, but is still included in AvalonMod 1.1.2.
Read on, everyone. I'm done here.
The Extra Accessory Slots were added because of the lack of accessory slots in Blah's opinion for the time, before Bullseye55 joined the team.
They use the code in Shockah's Accesory+ Mod.
They can hold any accessory item, and can also call the CanEquip, OnEquip, OnUnEquip, and other functions for mod accessories.