[Snake]

Uhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.

Sharpen is more a ''you focusing your power to hit your enemy with more accuracy and force' than actually sharpening your blade with Focus or whatever', same goes for literally any weapon and as stated by Spoops up there. It's just +5 Scaled Weapon Attack. The OP sounds fine enough, if not needing a buff to a maximum of +10 SWA, really.

This way it can benefit basic hits and autohits.