If this is Nemesis, under the exact same stipulations (plot device)
that plague her in the Ultraverse/Avengers arc,
then yea, she'd be vulnerable to a silly Ebony blade type attack.
But if this Nemesis, without the stipulations involved in said arc,
then .. that's a whole different story.
Nemesis, with full control of itself,
should be akin to what GOD is in the Omniverse.
(not TOAA ... more like the AE after creation or Sise-Neg at the height of his power)
Remember friends, Nemesis is supposed to be the Infinity Being,
and the Infinity Being was the absolute GOD of Marvel at one time.
(in fact, it created all of Marvel, including the LT plus the Infinity Gems)
Unfortunately Nemesis had a stipulation attached to it,
which was,
that the Infinity Gems which make up the majority of its power
had reached consciousness, and were battling Nemesis internally for control of self,
this made Nemesis ridiculously vulnerable,
even to an attack from the Ebony blade.
which is laughable.
(especially considering that plot device and all,
Nemesis was still able to obliterate the 616 and Ultraverse Realities,
and then make a new reality out of the debris left over from said obliteration)
The amazing part is, that the Omniverse did not collapse,
which suggests, Nemesis must've also kept the Omniverse in check.
(and that's an incredible feat)