Phase Arrow (Sp)
At 6th level, an arcane archer can launch an arrow once per day at a target known to him within range, and the arrow travels to the target in a straight path, passing through any nonmagical barrier or wall in its way. (Any magical barrier stops the arrow.) This ability negates cover, concealment, armor, and shield modifiers, but otherwise the attack is rolled normally. Using this ability is a standard action (and shooting the arrow is part of the action). An arcane archer can use this ability once per day at 6th level, and one additional time per day for every two levels beyond 6th, to a maximum of three times per day at 10th level.
I don't believe the intent was to have the attack negated by anyone wearing magical armor (given that this is a minimum 12th level ability).
Now, if you're talking an unattended object, I don't think that should count either. At least not a simple +X enhancement to armor(since it says it bypasses armor).
As to what constitutes a "magical barrier" that impedes this ability, I would assume they mean spell effects only, which would also exclude a ring of force shield, since that functions as a shield, not as a wall of force...
However, I could accept a ruling that you have to bypass the magically enhanced part of the armor to score a hit, but it's a stretch, especially for a 1-3/day ability.
