The +30 shield handle was an add on, while the -2 while in stance is a mod that can not be removed from the shield. In essence, it is an un-removable inscription. Thus making it inherent. The +30 shield handle is not inherent, as it was added on.
you cannot mod an uninscriptable shield unless you are 1 of a kind in this case grats this shield is unique and you ain't legit :P so check the stats again mate thx