the average damage stat you see in game is dmg/second (and is seriously rounded off). The damage upgrades effect the raw damage of an attack.
so.... even though the game says a individual fighter does 2 dmg/second... and after upgraded it still says 2 dmg/second.. the actual numbers would be something like:
Non-upgraded:
(rawdmg)/(reattack time)*modifiers
Upgraded:
(rawdmg*.3)/(reattack time)*modifiers
where modifiers would be dmg type vs armor type, armor level, and shield mitigation and any buffs or debuffs.
So basicly, you ARE getting your 30% bonus in attack... its just not displayed because on the info card the numbers all all rounded to whole numbers... but... you cant tell cause its rounded.
edit: that spreadsheet needs updating.