Two large firearms modeled after human pistols, meant for much larger targets.

Twin Heavy Bowguns

Both weapons fold for easier storage, banana clips hold extra bullets. The bullets are funneled into the revolver chamber and then moved into firing position. While they look like oversized six-shooters, they actually shoot around 20 bullets each. The clips are a lot longer than what the art shows, they take longer than you'd think to reload them. This has gotten in the way in previous fights.

Dark steel, wyvern scale and bone, leather for the handle wraps, and valuable gems for Agni.

~135 lbs each

They are very large pistols, mostly metal. Ignis has a white handle, and Agni has a red handle. Agni is also studded with valuable gemstones. The highlights look like brass, but they were simply stenciled in with a brass wire wheel.

They can be recalled to and from the Hoard at any time.

Of course, Yama wanted heavy firearms. But, they needed to be dual-wieldable and match aesthetically. Using some wyvern bone that he bought off of a trader, he sculpted the handles and colored Agni's. The gemstones were also aesthetic, no other reason than that for him.
In his usual fashion, both Ignis and Agni are gigantic. Either one has to be shot from the hip, and the triggers are a two-finger squeeze. Using both of them forced Yama to lean slightly back due to their weight, but his arms are able to bear the brunt of each shot.