On NA, 15-18 strength is almost a minimum. As Rubicon mentioned, TEAMWOUNDING is rampant. I personally wear armor to protect me from my teammates, I'll depend on shield or skill for the enemy.
Also, with a sword you definitely need at least 6 PS. HOWEVER. the Italian Falchion has cut damage comparable to an axe, so you -can- live with 5 PS and do fine. If by Italian one-hander you refer to the falchion, you'll be ok with 5 PS and the extra ath. Especially because it is short (70).
What I would actually recommended though, is to drop all your WM. Keep your 6 PS and get the extra athletics. You have an insanely fast weapon to begin with, so that is not an issue. But now you get to keep the extra hit points from the strength, do the same damage (6 WM can maybe equal to the 3 str 1ps??) and move faster. I mentioned doing the same damage...and lied. You'll have a higher acceleration, and thus a higher speed bonus, therefore more damage.