Can you give some supporting evidence? Not calling you out, but I think a lot of us are skeptical.
Wasnt the amount of resistance 'lost' also deducted from the character screen? I could have sworn ...
Anyway, unless the AS is incorrect, that shield suffix is new (for shields, that is).
Sorry, it has always been a prefix:
+ Light Radius
Glimmering +1 to Light Radius Amulets(1), Armor(1), Orbs(1), Rings(1), Staves(1), Wands(1)
Glowing +2 to Light Radius Amulets(6), Armor(6), Orbs(6), Rings(6), Staves(6), Wands(6)
It is not Glimmering, because there is enhanced defense, fire resist,
light radius and AR. 4 prefixes?
Also, if that 1 socket is a prefix, it would make sense for both AR + LR to be a single suffix, in the form of 'of the Light' mod.
I dont know, either AS is wrong (just like it is with 20fcr on scepters for example), or its new for shields, or just a glitch.