Kyranal is meant to be a mobility-focused glass-cannon assassin with strong sustained damage, but no sustain or durability. It should be very difficult to peel him off of a target, but he dies very quickly. This is my first custom champion, so I would appreciate some advice with balancing the numbers.
I pictured Kyranal as very similar to Kayle with a few exceptions. His wings would be black, and the armor would be more like Leona's Iron Solari skin, except that the helmet wouldn't have the wing motifs and would hide Kyranal's face. The cloth under the metal armor would also be black. Kyranal's sword would be as long as Tryndamere's but narrower and would be carried instead of dragging on the ground. The hilt would be black and silver, and the blade would be made of onyx.
Q: The active is Kyranal's gap closer - it's fairly self-explanatory. The passive aids initiation but also serves as a protection from counterganking and an aid to splitpushing.
W: Overhand strike is a basic sustained damage ability. It has high dps, especially at high levels, but is an extremely punishing short-range skillshot. The first cast - right after jumping in with Q - should be pretty easy to hit, but the rest will be much harder. Overhand strike can theoretically hit multiple champions, but in practice it probably won't ever do so.
E: Gut Strike serves as targeted damage and a slow. It would go third in the combat rotation after the first cast of overhand strike.
R: Reckoning of Darkness has multiple uses. In a purely 1v1 situation, its high damage and stun is a strong asset. In teamfights, it can be useful as an area effect crowd control.