Well, if he has a big Banner bonus, say 25 or 30? He might be somehow useful. Give him an innate Magic and Undead leadership as possible, to make him very versatile as a commander.
My best suggestions - give him some kind of really sweet ranged weapon by default, so he has some reason to actually exist. Then design him in a way that justifies giving him some kind of bonus item slots - if not 4 arms, then 2 heads, or 4 misc, or some combination thereof. So maybe he's not super awesome at the start, but once geared, is a totally sick SC chassis. That reminds me, a couple of other potential special abilities would really help his opportunity cost, such as Darkvision (100) (or Blind even), Regeneration, Trampling, Flight, Stealth, etc. Pick and choose, find something that works with your concept - just as long as it's not nothing, a lack of specific reason to use him, will result in his non-use.
