i respeced to 13pd archer yesterday
That was mighty silly of you, when people shout "Don't respec straight after the patches", it's because they know changes are bound to happen. I'm not sure I understand why anyone in their right mind would think that it was intentional to make 13 PD super accurate and high damage... It was already said that it was a PD miscalculation which was being changed from 15*PD-1.5^PD to 14*PD-1.4^PD (therefore 13 PD would have a 102.6 wpf reduction).
I can't say much more than that, but with this change I would say that 13PD is very inefficient. 10PD being the maximum useful due to the +4 above bow requirement limit, so your damage increase would be capped at PD*14% so +140% of bow & arrow damage along with however much wpf you can put in. With 13PD after this change you'll be looking at having a reduction to roughly 8.5PD on wpf reduction but you could get more wpf back if you just invested it into agility and weapon master.
Anyway, don't respec straight away, wait a couple of days for things to be sorted out and tweaked, chances are there will be more errors or things that'll be adjusted so don't make the mistake again!