A request that fortunately turned out not to have any of those messy problems which keyblades tend to....
Specifically, I got this from a high-resolution (cutscene) model of Axel ripped out of Kingdom Hearts II: Final Mix.
As for how to properly size this papercraft.... Compared to the model of Axel that it was a part of, when you hold this weapon in the center, the tips of the longest spikes should come up even with your elbow. Hold a yardstick or meterstick against your forearm if precision really matters to you and you want to be 100% sure before you print it out.
(I really need to do a drawing of myself tucking motivation under my arm like a football and running for my life........that describes how I work only too well.)