[Taqwus]

I don't think I've ever actually seen somebody get paralyzed from attacking a commander wielding Aegis, and I've quite frequently abused it against the AI. Killed, yes, but paralyzed?

Blood vengeance is not too likely to work against the wielder of magebane; even if it applies to other effects than direct hp loss, it's defeatable via MR, and Magebane gives a healthy bonus and as a nifty unique artifact is unlikely to be handed to somebody who had a mediocre or bad MR in the first place... and I don't think Blood Vengeance works against instant-death attacks e.g. Petrify.

As to Magebane's power, well, it's completely unresistable +100 fatigue. If you're wielding it, you probably also either cast quickness, or have Jade Armor, or Boots of Quickness, meaning a decent chance at delivering +200 fatigue in addition to the regular damage. That's rough. I've seen Mandragoras take out a Naga due to fatigue... Magebane is very powerful in 1-vs-(1 or few), but not as purely destructive against massed chaff as, say Sun Slayer or the Unquenched Sword, and doesn't life drain so for a living commander you'll need another reinvig source.