Broadsword: 4d6 = 4-24 pts.
Battle Dress TL 14: Protection 18
With no other modifiers, must roll a 19 or better to do 1 pt or more of damage. Chances of rolling 19 or better: 10%.
Chances of doing 4 pts or more of damage (rolling a 22 or better) are 1%.
Chances of doing 6 points of damage (rolling a 24) are under 0.1%.
One thought is that it may be rare, but it should be possible to damage the battle armor. A well placed hit in a joint might bend something just enough to cause it to seize up or at least reduce mobility. Perhaps some of the damage should be to the armor and not the occupant.
Another thought is that an attack, especially a surprise attack from behind while you are preoccupied crushing townsfolk between the toes of your mighty battle dress (sorry for being a little silly there - wait, no, I'm not sorry!) anyways, a surprise attack from behind might throw you around (as the battle dress automatic gyros compensate to keep upright the force exerted on the armor is now transfered to the occupant. Luckily the armor is designed with cushioning that greatly reduces the forces actually caused to the occupant) 1) if you are not strapped in tight you slam into the inside of the battle dress or 2) if you are strapped in tight, the harness or whatever may cut into you or put strain on your joints. If you will, imagine a car slamming into another car where the occupant is either thrown around the interior, has bruises or worse from their seat belt, or has whiplash.