One more point is the walk path is only used to position the body along the path. Once you apply a walk to the path and figure the motions are recorded as key frames in the animation palette and you can change/delete the walk path and it will not affect the currently applied walk. You can also go in the animation palette and move/change any key frames you want. So if you want to move the arm to a different position you can and it will not affect the rest of the walk cycle.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13