I think ur mistaking Physical Attack & Flat Elemental Dmg , Paladin3 sanctuary gives Flat elemental damage not Physical attack haha , it is good however definitely strong for an Auto Attack party , not a Burst Physical party though .
Physical attack goes through skill % & attribute % , which is the main reason why distortion is the key player in achieving max damage , because Distortion gives [ 25% bonus Physical attack ] . Let’s say headshot is at 1000% ( just an example ) and we use scout distortion , the multiplier now becomes 1250% not 1025% and that means the higher the skill % , the higher it get’s multiplied by distortion , which is what makes it so amazing with a Burst Musk .
The video below is everything and anything about Sanctuary .

& distortion works for any Physical dps not just my build .