This seems like an extremely petty complaint.
Yes, you jump and cut. But the cut is downward, so you and your sword are plunging down on your enemy.
Technically, cut is even a misnomer, since that implies lacerating flesh by movement of a blade across the skin. What you're actually doing is trying to cleave your enemy in two, so if you want an absolutely perfect literal description of what the move does it should be "Plunge Cleave." (Naturally you can't actually cleave anything in twain because MMO mechanics, but if you're going to be pedantic like this there you have it.)