There isn't an option for, 'make the item better!'
I wouldn't mind if the slave collar gave the wearer the feeblemind affliction, made them mindless, and put up an autocast 'sabbath slave' every battle. That would at least make it worthwhile in my mind.
Basically it would kill some slaves and then turn a commander into a slack jawed idiot who fed a sabbath/communion who either helped you win the battle or died for lack of being able to rout.
Is there a way to mod any of this into the item?