The manual says,"Extra attack, luck, ethrealness, fly, cursed, fear+25, spell
d lesser horror, dangerous, automatic call horror at start of battle, curses weilder, slight chance of horror mark"
A couple of points here, its got alot of powerful effects, so you could make a temporary powerful SC but it would be a good idea to pull the rest of the equipment off him at some point and just lose the gift?!?
If you gain horror marks, the automatic horror at battle start is going to attack the gifts weilder, so you need to be able to easily defeat horrors.
You could just equip a expendable character and just use the send horror spell each turn until horror attacked.
It costs 40 blood slaves, is it worth it?
Also why have so many of the unique artifacts got drawbacks?