I use max damage / ar charms instead of psn on my bowa and they work great. And if you are going for damage, a p up'd buriza does more than faith. I also have 4x 15 res gc in my inventory (no skill gc's) cuz bowas have crap res as I'm sure you've noticed. I use:
120/45 diadem
1600 28 res BW Fort
200ed Up'd Buriza
cat's eye
2x 20 dex 240+ar ravens
tgods
crafted gloves with 20ias, kb, dex, and str
gores
I'd like to use a Treachery armor for the venom, fade, and 45ias but I'd lose mucho res and def - dunno. Now I just need to trade for a pride for my merc