On the Compendium it shows Voltaghesit psalm to add Damage Reduction but it gives +10 shield on hit, not sure which it's supposed to be as the patch just came out and the compendium shows Damage Reduction.  Theres other things that don't line up with the compendium and I'm not sure if it was changed and the compendium wasn't updated or they just aren't working as intended.

If Voltagheist Psalm is supposed to give +10 shiled on hit it doesn't stack with Aegis in the same piece of gear even though they're different psalms.  In case someone else is reading this psalms don't stack with themselves in the same piece of gear.