In the Espada Arc, Kenpachi fights Nnoitra.I was trying to explain Nnoitra to my friend but I couldn't figure out what kind of weapon it was, is it a scythe or what?
Nnoitra's zanpakuto, Santa Maria, is unique in regards to what type of weapon it is.
Unreleased, it resembles an axe with two crescents or a halberd, with it's edges rotated by 90 degrees.
But due to the placement of the blade edges, it resembles a scythe more so than an axe.
When released, it resembles a scythe:
But note that when he was the 8th-ranked Espada, his weapon resembled a staff with a giant crescent:
Note that it does a similar motif to the Chinese monk's spade (aka Crescent Moon Spade) weapon that's like a halberd.