I seem to recall a +ATK cap from worn and/or spell items back on Phinigel... but do not recall at what expansion it came through or what the value was at the time. Just that +ATK values seemed not to benefit the values shown on screen at the proposed rate. Felt like there may have been a Soft or Hard Cap to that effect. Anyone know if there are concrete numbers for this one way or the other coming up on Aradune now that it is hitting an expansion with more +ATK gear?
Worn atk cap is 250. Then you get AA that increase the Worn attack cap in OoW. There is no +ATK for spells.
Sleepers weapon avatar proc does count as worn attack as far as I know. A shaman casting the buff doesn't.