They do include the "heavy" and "loading" keywords in the description of the heavy xbow, but those don't affect gameplay at all
Heavy crossbow actualy is heavy ... kinda too heavy to my liking to be honest.

It made me choose bow instead (this, and the fact that i just dont like crossbows at all) ...
And please feel free to corect me, but dont "loading" only means that you cannot attack the weapon twice in single turn?
Therefore it should not have any meaning before level 5? ... Or is that suppose to include potion of speed?