Serpant ward isn't in "wcs_ability" its in WCSfunctions\WCSskills\es_WCSskills and then after it retrieves the values it loops the block "wcs_warden" in es_WCSultimates.

Presuming the block "wcs_warden" has a line included with something like "es_xset wcs_tmp 0;es_keygetvalue wcs_tmp WCSuserdata server_var(wcs_targetid) swardinvul;if (server_var(wcs_tmp) = 0) then warden_run_#" then the following would work. Otherwise serpant ward will not check for swardinvul.

es_keysetvalue WCSuserdata event_var(userid) swardinvul 1

the weapons restriction has broke again on 0.77 never had so many troubles with it...