Currently the Barrier:Devotion attribute is just suicidal to use on any content that requires party-play and endgame equipment.
The Barrier:Devotion attribute should be changed as follows:
maximum attribute level 5
takes damage for party members inside the Barrier
converts 10% of the magic defense improvement per attribute level into physical defense improvement (only applies to the caster)
reduces the casters armor durability loss by 16% per attribute level while inside the barrier
With said changes, Paladin receives only 20% of the durability loss when taking damage for the other party members (which at the moment takes a heavy toll on equipment durability) and it provides an actual use for Barrier even in solo-play situations as it prevents the equipment from taking too much damage.
The physical defense boost should not come without a downside, so a simultaneous reduction of the magic defense boost could help the skill to become more balanced at the same time [a level 5 Barrier with level 5 Devotion attribute would feature +25% physical defense and +25% magic defense, as to not outclass Sanctuary]
That way the Paladin becomes devoted to his equipment and the party and can fulfill the role of taking damage for others without having to risk his armor.