where could one learn this ability?

this only works for warlocks, mages, and priests. you cant train this anywhere. if yo are one of these, then go to spellbook then in general tab, bring shoot down to your action bar.

Interesting bit of information:  It seems my wand projectiles are procing Fel Synergy heals.  This leads me to believe that "Spells" count for any casted spell, and "Spell Damage" counts as any non-physical damage, such as wands would deal.