I've tested Ranged Power Stance and the Bow Ability with Ricochet and Fire Arrows.

Bow ability seems to enhance Fire Arrows (and I guess all special arrows then).
Ranged Power Stance does not seem to enhance Fire Arrows (8-12 expected with the buff, from 6-10, with 7 and 13 tolerated due to rounding, 6 found).

Both Bow Ability and Ranged Power Stance seem to enhance Ricochet (28 damage done with the starter bow, 2 in bow ability and power stance activated), which never crits.
Hence, Crossbow Ability probably doesn't enhance marksman skills.

Last edited by Chrest; 17/03/16 02:38 PM.