[Edi]

Easiest way to take down a sphinx in combat: dusk daggers and gate cleavers. Both cause armor negating damage, and tossing a squad of mid to high level thugs armed with these weapons will chop the sphinx up in no time. Especially the gate cleaver, 29 armor negating damage is quite a wallop. Machaka should have no problem producing either one of these, as gate cleavers are earth only and dusk daggers are earth/astral, so you just need a random astral pick for black sorcerer.

Edi