It's not an attribute, it's a param. You can't just send it server sided, you have re-pack the item defs for the item you want to change except add param 258 or 259. This could have other effects though since the only items that contain those params are skillcapes by default, and that param could be used in other client scripts. I think Matrix has named the field "clientScriptData" or "clientScriptMap" in the item definitions decoder.








