This is a posable, high-grade or better injection-plastic kit of an item from the Gundam universe.
Gundam Astaroth from the manga comic: "Mobile Suit Gundam: Iron-Blooded Orphans Moon Steel" gets an HG kit release from Bandai! It's equipped with a knife, a demolition knife (which can be modified to be in its storage form), and a rifle; it can be customized with parts from other similar kits as well.