[GAMEPLAY] Runeglaive interacts oddly with on-hit abilities like Draven and Thresh

Runeglaive seems to interact... oddly with Draven and Thresh, perhaps others that I haven't tested. Runeglaive doesn't seem to work with their on-hit abilities when they crit.

REPRODUCTION:

1. Pick draven or thresh with smite.
2. Get a runeglaive and crit.
3. Build up Thresh E/Cast Draven Q
4. Crit with runeglaive proc
5. Runeglaive and base damage crits, draven axe/thresh E damage disappears completely?

Probably a moot point next patch, but this might work with other on-hit items with Nidalee or Poppy. Conversion to crittable magic damage seems to ignore on hits?