yes you can add some new skill... if you don't increase your masteries, the gap will remain the same. The gap is between your character's level and your HIGHEST mastery.
So you want to max bowman mastery AND pick some melee weapon skills? It will be a waste of SP IMHO. Anyway if you want to, choose glaive or blade (neither sword nor spear). Glaive does more damage, but with blade and shield you might block some hits.
GLAIVE : soul spear serie + ghost spear serie
BLADE : illusion chain (PVE) / hidden blade serie + killing heaven blade serie (PVP)
it's your choice... but if i were you i'd rather give up the 2nd weapon mastery and go for a 2nd force mastery (cold for defense, lightning for speed or force for ressing other people).
