War Domain Cleric, three attacks per turn, does this work?

Attack with a Shortsword, War Priest allows me to make a bonus action attack, have the second weapon be a Light Hammer or Scimitar, Nick property allows that attack to be made as part of the attack action (at advantage because of Vex from the shortsword attack). Use the now still free bonus action to cast Spiritual Weapon for the third attack. This seems right to me but I get mixing rules wrong sometimes, what say you?

You're correct. I forgot about needing to having Masery, I keep thinking Mastery and Proficency are the same. I checked the character sheet I'm trying to build this character on and the Mastery Icon is not lit for the shortsword. I know multiclassing would allow me to do it but that is what i was trying to work around. Thanks!