I can't believe I just noticed it now, but it seems knockback is only applied to base damage rolls. Extra traits don't seem to affect this at all, which seems odd because you'd usually think a harder-hitting weapon = more kick. Adding damage mods, on the other hand, does increase the chance of knockback. This is most easily seen in AoMr, where SoG has absolutely no effect on how far you can throw baddies (whereas damage mods will allow you to knockback spiders with ease). Any thoughts on this?
EDIT: I also want to say that something is definitely off with SoG (or the listing on the wiki for HP is incorrect). I can confirm that it took 3 shots to kill a human sergeant without any armor on, while I had 3 levels in SoG. I'd have a screenshot of my messages, but it seems pressing F10 while in the past message menu doesn't have any effect; I guess it only works for the main screen and not any of the sub-screens. In any case, either the human sergeant has at least 15 HP (1+6+1+6=14), or the damage bonus is only +1 per level (1+3+1+3=8).