The skill has not either a valid skilleffect ending, killing the animation after finishing the given time, or you are totally missing the duration of the skill.
E.g., if a skill animation (which Joymax did) lasts in total 5 seconds, the cast period goes for 1 second > where the chinese character gets his stance back, 1.5s > keeps whirling around with his arms, 2.5s > pushes forward, nazi greeting into mid-air, and finally getting back into the regular standing stance, if this hasn't written to the skill itself (those Action_PreparingTime, Action_CastingTime, Action_ActionDuration parameters) correctly, it will bug out.
There were some Lv 125 skill (that buggy release few years ago), which no one bothered fixing. Few of them having wrong time related action paramters.
You have to do it yourself. Fix it, how you think it might fit in, and test it. Hasn't worked: keep going on with it.
About the skilleffect animation killing, there is a tab which is called "Kill", check other skills, and you might get a clue whenever that parameter will be set to 1 instead of 0.