It's not precisely broken.
It's just not necessarily working as you might expect.
Puncture Shiled (as far as I've worked out) increases "visible ranged defense" by 50% this is not the same as "invisible ranged defence"
Now the only visible ranged defence a player can have is from Marksmans Song, (139) so PShield increases the ranged defence when you are buffed by a ranged ton by about 70.
70 defence isn't much at all when hunters/archers can hit well into 5 digit crits on toons.
Needless to say I have reskilled and removed this skill
What would probably fix this issue, is if they made ranged defence a visible stat on the stats screeen, then I would bet my bottom dollar PS would increase that number by 50% as clearly defense does have "some" effect on ranged physical DPS, it's just not much I think