You need to rotoscope to do the true light sabre effect. Photoshop isn't designed for moving images. People do it but it's a huge pain and the motion quality will never be as good.
yeah i do use photoshop and yeah it is a big pain going frame by frame but i'm looking into vision lab at www.fxhome.com have you or anyone heard or used it before???
Commotion was the best for this but when Pinnacle bought it from Puffin designs they basically threw it in the garbage. You may be able to find an old version for cheap on ebay The best thing now for Mac is Shake but it's the price of a car.
The problem with trackers is when they swing the sticks which happens a lot in most of the action sequences. Then they just become a long blur. Key frame roto on the extreme frames gives good results.