58 ninja here, I would tell you what I did, but note that I was pretty poor up to a certain point where I just grinded pirates big bucks. I would get all AP accessories witches and marks to PRI. As for weapon, you should start rolling NV for kzarka or stick with/Get a TRI liverto. I would not get a TET because it is much better to get zkarka down the line and use the TRI for failstacking. For armor, boss pieces should be in sight now especially since you're at 57, but if not possible get all grunil DUO. Again, try to roll NV for any piece and buy it, but aim straight for bhegs since they dramatically increase damage. Right now acc/ap is very important for pvp, I wouldnt worry much about DP. If you want, buy a +15 acc offhand and +15 ap offhand and get the ap one to TRI. Switch them on and off until you get bhegs. +15 acc off hand is roughly 15mil. Once you get bhegs and muskans or bhegs and another boss piece, switch to some two piece heve and get that to DUO or TRI til you get your other pieces since the HP is very important.