An Ion Axe weapon for minifigures with 3mm clip hands. Scaled for Kreon minifigures, the Ion Axe is ~33mm long from its hilt to the tip of the large blade. Also works with Halo Mega Bloks Spartan minifigures.
Note: This weapon has a 3mm handle. If it feels loose in your Kreon/Spartan's hands, apply a layer of superglue to the handle and allow to dry.
The Ion Axe weapon will fit in Kreon Optimus Prime's wrist in place of its hand, however one would need to use some layers of superglue on the handle, else it will be loose.