[Vuejs]-Vuetify modifying inline edit data table content from method

You have to pass the updated iron value to save() along with reference to the updated object in this case let’s use name (in real example use some unique id)

          <v-edit-dialog
            :return-value.sync="props.item.iron"
            large
            persistent
            @save="save({name : props.item.name, props.item.iron})"
            @cancel="cancel(props.item)"
            @open="open"
            @close="close"
          >

in save() implementation , update iron field inside Data object based on name field,

save({name, iron}){
//  update `iron` in Data object based on `name` 
}