light = utterly useless at capped lvls. the only thing u really benefit from it is phantom, and if your ok with that loss then ice or force r better substitutes.
the reason ice is good: snow shield, extra phys def (which u really dont need), and freezing skills.
the reason force is good: res, debuffs, therapy circles for those "oh shit i g2g brb a sec" moments, and for group pvp (most dont realize it) force is still a good choice u can debuff all your opponents and still have similar tanking ability as snow shield because of impotent.
personally for bow builds this cap im going: fire/pacheon/force 90 with ice sub at 30
here's my guide:
viewtopic.php?f=5&t=88484. i still need to edit it for a ice @ 90 tree and the SP requirements for it, but the same stratgies apply as u dont get any new skills by moving it from 30-90.