Why is shield swipe so bad?

[Cyrus-Wallace]

This is a DPS ability? Potency is 10 more than savage blade. The average potency of paladin 1-2-3 combo is 206. You basically add 4 potency onto one ability by interrupting your 1-2-3 combo to use shield swipe. Try again.

The only "advantage" is its low TP cost and the fact that it doesn't interrupt the RoH combo.

Edit: Oh, you edited. No, it doesn't interrupt your combo.