I have an idea for a sack/barrel/crate that's actually visibly held by the mob, and gets dropped much like a torch does when combat starts. of course the container would have loot in it, so that's another wrinkle...

I'm picturing goblins carrying barrels on their backs, stockpiling supplies in their keep. This is more of just a fluff request, but it would be nice for what i'm trying to do.

any help?

You can't equip containers, but you could make a new "light"-item (ie a torch) using the model of the barrel or whatever, which would be dropped under said circumstances. You'd also need a script with an OnRemove-block which replaced the barrel "light" with a barrel "container".

I'm not particularly good at modelling, and I don't know how to tie meshes to specific spines in the creature meshes, so I'm afraid I can't help you implement it