Messing around with the Item Icons offset I found that you can have two sets of Icons, one for the stats and other for battle screen and messages.
The pointer at 0x4E20 is for the stats screen, and the pointer at 0x4EF4 is for the battle screen.
Both use the same index, if a weapon uses the index 0x01, it will show the icon at 0x01 in both sets.
I think this can be used for some effects, like transform a Dragonstone into Fire Breath.