When I played an El AR2 things that stood out were 1) Elemental Arrow I II III were just plain worthless and 2) there was no Energy attack. My suggestion is this:
Remove Elemental Arrow and in its place put 'Energy Arrow' I II III which does Energy dmg. and hasthe same mechanics as the 4 existing elemental attacks with a scaled chance (5%, 10%, 15%?) to proc a dmg. kicker like the old Western Deadlands Stones, scaled to tier. The Glowing Beveled Stone, for example, was a lvl 55 crystal, gave 96-131hp extra dmg on 5% of hits. Just using that as an example because its the only stoneI have access to, and because 3 of 4 existing El Ar attacks duplicate to some extent effects from the WD crystals.