Is there anywhere else an item can be attached other than the hand? Can an item be activated and attached to somewhere else on the actor?

Or, alternatively, is it possible to have the item appear on the actor, but not move when the actor moves its hands?

Devices can be attached to hands, usually the foreground hand. In the case of shields and dual wielding, (which is really just fooling the game into thinking the offhand gun is a shield) the device is held in the background hand.

Devices cannot be attached to other body parts, or anything else.

While the device is in the hands, it can be activated by holding the trigger, or by AI trying to shoot stuff. Lua cannot access it while it it is held, because it is seen as an extension of the actor itself rather than an independent object.

While the item is not being held in the inventory or hands of something, it can be accessed by Lua. Case in point: viewtopic.php?f=4&t=10370&p=278901&hilit=pulse+digger+epic#p278901

However, an AEmitter may serve your purposes, but I can't know that until you explain to us what you're trying to do.

Just like, say, something like a stick attached to what looks like the actor's back. Doesn't even have to do anything. Just that when you have the item out, it appears to be on the back. When I do this with offsets, it doesn't look right when you move too much.