I would think that, theoretically, there would be eight sword slash directions possible (not counting the stab) in Skyward Sword, given that many targets such as training logs look like they only accept horizontal, vertical, and 45-degree diagonal slices. But animation-wise it looks to me like there's quite a bit more than that; for example I've seen uppercuts launched from both the left and the right side of Link's body. So what's up here? Are there 8 directions with multiple animations each? Or are there more directions (say 16), and which ones correspond to the eight major axes (assuming that there are only 8 "basic" directions)?
From what I understand, there are 4 "basic" attack types in Skyward Sword:
In additionally, there are the two stamina-powered spin attacks:
Finally, there is a 'final blow' attack that can be triggered when an enemy is down. Swing down both wiimote and nunchuk while Z-targeting to trigger it.
The animations take your sword's prior position into account, which might account for some of the variation you're seeing. With 3d animation, there are no "frames" like you would get with sprites. So the "animation" might look a little different depending on where Link's sword was initially, but it's not to the point where "sword down and to the left at a 40* angle" gives a wholly different animation than "sword down and to the left at a 42* angle", even though these could potentially look visually distinct.