Changing "Lantern" More Advanced.

[Darkfire]

1. The arm and lantern are one model, if memory serves.
2. I think it's impossible. Or nearly.
That's because the lantern model is set for the whole mod somewhere in the files (and you have to do a full conversion to do even that)
So unless you're able to somehow influence other files by code executed in-game then it's impossible. But if you can do that, you could code something to replace the model file with another one therefore changing it in-game. But even if it worked it still might crash the game.

PS. I'm quite sure if you'll change the lamp item (the one you pick up) it will still make the old model appear. It's like with tinders and health items: if you replace tinder item for matches (or anything else for that matter), they will still light candles, if you replace laudanum with health kit they will steal heal... The lantern is this kindo of item.