the core abilities boost up spellpower if you do not use the runearm... but there isnt any interesting enchantment to stabilize the charge enough:

suppress the enchantments who makes decay slower 25% and 50%

put stable overcharge2 at tier 1
put stable overcharge3 at tier 2
put stable overcharge4 at tier 3
put stable overcharge5 at tier 4

the +1to hit +0 damage enhancement for repeating xbow is "unfair" versus all the other weapon getting +1 to hit +1dmg
so, for 2ap you get +1 to hit, but if you spend them somewhere else... you can get up to +3d6 sneak attack damage for the same ap.

about weapon attachment: ddo is a game of switching gears, especially weapons...
the "keep the weapon stuck to your hand" mechanic is about fun as the "wait for all the party members, yes even for the dude afk for 30minutes quest mechanic"

it is borderline "fair" for barbarian who cant use scrolls while raged but just drink potions... for other classes doesnt feel good.

-----------------
about the arcano technician tree my only concern is the lightning bolt NOT being a SLA