i don't know if i'm right but souls of purgatory are like cartuccia for God-castiel...but this weopons gonna empty after god-cass'll killing all his enemies in heaven?

maybe i misunderstood...but it seemed that castiel needed souls to arm his weapon and killed raphael...so each time he killed o gonna kill someone he Lost cartrigde, his weapon will ended to be empty?...am i right o wrong? am i misunderstood something in the explanations of 6th season?