About the attribute "Unknown 2" in Item Editor → Weapons for AoS...

[TsukiZero]

I opened someone's romhack and noticed two weapons, while sharing same GFX and Sprite indexes, have different animations. Then went to check in the Sprite Editor and turns out that it has three animations: 00 (used by Kaladbolg, Slash attack) 01 (unknown usage) and 02 (used by the Broadsword).

This leads me to believe the Unknown 2 attribute, given its position, is "Animation Index"

The hack in question is "Castlevania Aria of Sorrow Weapon Patch"

Confirmed: Unknown 2 IS Animation Index