The only really bad thing in this build - absence of weapon skill. On higher levels and with big survival bonus, weapons that drop from enemies will have much higher level than yours. You will have speed penalti from that.
Cast speed of Devout Guardian CAs will be half of what it could be with skil.
But you can compensate speed with +%casting speed
This build also dependant on +skills bonus, you should have a lot of sockets with forged +skills rings and amulets. Good that you have bargaring skill - best source of jewelry.
This character is very strong against bosses. If you using Jolting Touch + Deathly Spears combo, you will kill boss with spears very fast, while being invincible. On high levels spears can do 7 attacks per cast, and boss can be hitted by multiple spears.
Which attributes you increasing? I advice stamina(for regen time), vitality(more health) and willpower(more shield).
Amplifying Discharge can be very good for magic focused character, but is not good for your build. I like 2 Ice bullets + Ricochet.
Some Source Warden skills are actually very good if modified.
Fiery Ember can buff all you fire damage by 50-70% on high levels. If you dedicated to make it good - it can fast kill everything in a big area, exept champions and bosses.
Icy Evanescence is the same but with ice. I like to use it with Amplifying Discharge.