Superior potency is listed as being 0. This is by far the best tanking enchant a paladin has out there atm. It could do with being a 15. Greater say a 12, and standard potency a 10.
Nalumis's figures are correct. Note that toward the three-target end, Hammer is the most important ability, and against a shingle target the Shield is. The below chart is by itemization level, and assumes an indefinite 969 rotation with inifinite mana (tank and spank).