Yasuo's sword

So, what kind of sword does Yasuo carry? A tachi or a katana??? It's unusualy long for a katana and has a shorter handle than a katana, just like a tachi but it has a mild curve and is carried with the cutting edge facing up just like a katana...

So, what is it? A tachi, a katana or a hybrid of both???

Any rioter has anything to say? Maybe the one that developed yasuo???