uhmm...
an item while you hold, causes a spinning blade to come out and circle indefinately around the player in a complete rotational manner, perhaps 1rotation/3seconds, causing damage to any unit it contacts... if the blade hits a wall or tree or something it bounces off and starts rotating around the unit in the opposite direction
using the item causes the blade to shoot out perpendicularily away from the player based on its current position, stabbing anything in the way... contact with a wall or tree in this stage could return the blade or cause it to drop (item moved to location)
or if u want something simpler, like variability potions, which randomly bestow a multitude of effects on you randomly