Well - the answer is kinda both of the options.
I imagined it fire a disc, but not a whole circle, like with "wings" (like the shape of the moon when its not full).
That disc explodes in a grenade-like function into hundreds of small fragments that are burning with blue plasma acid.
So the effect you see is a straight flat plasma burst, and kinda like a shotgun glowing particles flying towards u at high speed :D