Figured there are enough fusions now to make a gallery here. Right now the gallery is up to date, and I'm planning on updating it as new images come out, but if you want to see new fusions before I upload them here, the source for them is here: https://www.deviantart.com/krystalizedart/gallery
Looks more like a mecha arm here, but the weapon Asami tends to use is just a glove that can electrocute people. Used heavily by the non-bending Equalists in the first season, because it lets a non-bender quickly incapacitate even a bender if they can get close enough and use it, and is a lot more easy to hide than a more traditional weapon. It's also more child friendly than stabbing someone with a sword or spear.