From my understanding of the mechanics of magic it is unlikely that there would be a magical item as generally simple as a ring could do something like a double weight enchantment as a passive effect of the shield. I think mechanically it would be more likely that the ring is a double focus ( Ragen could probably make a tool like that ) Part kenitomance physical shield part terramancy gravity focus. Focus on the shield spell and you get the shield out of it focus on the terramancy spell and you get perhaps a spell that increases the weight of a target as long as you hold the spell in place. I could see it being a handy tool to give to a hard headed puiple who likes to follow their mentor into danger situations. Protect you from monsters or slow them down enough for you to pull out a escape or attack potion or something.