Chainsaw

A chainsaw, while not as immediately gratifying for an insane agent as a flamethrower, is also a nice weapon for an HQ-wide rampage, in that while there is not as much fire damage going on there, there is much more blood-splattering going on.

The Flowers that are some species of tree, and thus woody, are likely in more danger from the average chainsaw than from any other sharp-and-pointies that an agent might possibly have, unlike the greener and more floral sort of Flower.

This is not an appropriate weapon for use against zombies except in the Evil Dead continuum (because that would only spread most zombie infections or just be purely ineffective), or Sues in general (because it gets glitter everywhere).