Ky Kiske was a member of the Holy Order of Sacred Knights during the war with Gears. After the war ended, he became the head of the International Police Force. He uses lightning, which is considered the most difficult type of magic.
In-game, Ky's move set resembles that of a Shoto-clone in that he has a fireball and an invincible rising slash, and his long sword strikes allow him to play a dominant mid-range game.
Ky Kiske's name is a shout out to former Helloween member Kai Hansen (now a member of Gamma Ray) and Helloween member Michael Kiske.
An incomplete list of Ky's special moves, with inputs listed in numpad notation.
Stun Edge (236S or 236H) - Ky shoots a bolt of lightning straight ahead. Depending on the game, the HS variant produces a faster version, or a charged, multi-hitting version of the move. Can be used midair to cover certain diagonal angles on the screen.
Vapor Thrust (623H) - Ky performs an invincible rising slash. Often used in combos or as a reversal, but can miss opponents who are too low to the ground. Can be used midair.
Stun Dipper (236K) - Ky slides on the ground toward the opponent, ducking under many attacks. Quite risky for Ky if blocked.
Greed Sever (214K) - Telegraphed, overhead-hitting move which can start a combo on hit. Can cleanly beat low-hitting moves.
Split Ciel (236D) - Unique to Guilty Gear Xrd, Split Ciel staggers an opponent on hit, and leaves behind a seal which powers up Stun Edges or Sacred Edges that pass through them. Empowered stun edges leave behind a large sword which either instantly strike toward the edge of the screen, or grind through screen space at midrange.
Sacred Edge (236236P) - Overdrive move which uses 50% tension. A powered-up Stun Edge which is useful as a combo tool.
Ride The Lightning (632146H) - Overdrive which grants Ky invincibility for an extended period of time and rushes forward, hitting several times. Occasionally useful as a reversal against moves which go under Vapor Thrust, or as a combo ender.