Protect and Resist (both Cleric skills) should give more def, M.def, M.dmg, dmg w/ more peoples in the party but it doesn't
My def w/ 2 additional party members
http://prntscr.com/3aokvt
http://prntscr.com/3aol1z
My def w/ 3 additional party members
http://prntscr.com/3aol8e
http://prntscr.com/3aolb1
It's also bugged w/ 4 peoples should give 60% more deffense w/ 4 additional members