i have a similar idea, i call it a 'skipper'
basically, it's a little manhack-like thing with the blade vertical rather then horizontal- it's essentially a small playertype with no air movement and does damage on-touch. every time it hits the ground, or "skips", it bounces into the air toward the nearest player spinning it's blade wildly until it hits the ground again, where it repeats the process until it finally cuts something to ribbons
maybe it could even come from a gun