For whatever it's worth, in a quick test game I sent a Mother of Serpents with an Eye Shield up against an SC with an attack of 17, Prot of 16, Def 19, MR 18, Morale 30. The SC killed the Mother of Serpents in three or four hits and didn't take an eyeloss, so the eye shield is hardly a deathtrap for SCs. You could probably get away with using Wraith Lords or Wyrms, or any SC that will regenerate its eyes on the rare occasion that it loses one.
-Max
Edit: Whoops, I forgot that recuperating Wyrms is one of my house rules. Kraken or Tarrasque, then. Not like either of those is going to be available mid-game, though.
Edit2: one more datapoint--my SC had nature magic, and I forgot to script it, so when it was attacking the Mother of Serpents it had 99 or so fatigue (she rushed up to melee range but lost her serpents on the way to some Earth Shards or whatever they're called). But she had 136 fatigue, because the first thing my SC did was cast Sleep. I don't think that affects the eyeshield, but if fatigue did somehow affect the ability to use the eyeshield that would suggest a couple of obvious counters, like, oh, Magebane.