Sharpness does not work as intended, as it does not increase damage, visibly or in actual damage

As seen by the screenshot, a Sharpness 4 diamond sword still does only 7 damage, the damage of a base diamond sword.

This can be replicated by simply enchanting a sword with sharpness, via either an enchanting table or an anvil.

Tests show this isn't just a visual thing, the sword actually only does 7 damage