the visor is valkeries mask i believe and the weapon is a rune type item i cant tell what it is because its cut off but itd guess its an axe/scythe edit: i was wrong its not a axe/scythe its a mace =P
Yeah this seems to be the NM you fight for the samurai boots. According to mysterytour you must go to the secret beach in the dunes at nightime and click on the ????. This NM spawns along with another (Onryo).
he looked like a shadow-ish thing, like ka and doppelganger, wearing scale armor, and using a staff or hammer or club. pretty sure it was either a mace or hammer. hope that helps