>>395126303
You have to use workarounds like multiple sub particle systems or something like that. You can't just have a single performant particle system that you get to push a particle out on game object enable. I think the way Unity works is that it doesn't refresh particle systems by default, so after you enable the game object and the particle fires, and the loop reaches the end, it'll just stay ended even if you disable and reenable the game object. I think most semi-auto guns are using a multiple particle systems to get around this but don't remember the details.

HOWEVER, since you are doing an effect that depends on collision, this is easier. Create a particle system that has an invisible particle or particles that covers the span of your sword. Make it locked to the relative position of your sword with 0 velocity. Put your desired particle effect as a child of that. Then make it so that the invisible particle colliding with something spawns the sub particle system. These are all settings within the particle system just look for them or Google.