Koga possesses a weapon named Goraishi, which becomes his most powerful weapon. He is also seen carrying a sword, but he doesn't use it often, only in chapter 340 against Mouryoumaru. In the same chapter, he reveals that he took the sword from a human as "decoration," and he didn't think he'd have to use it.
After suffering serious wounds, Koga is partially restored by three Shikon shards embedded into his legs and right arm. The shards are eventually taken away from him by Naraku, gravely weakening him; he leaves and disappears from the manga, after telling Kagome that she may leave Inuyasha and come to him at any time. In the epilogue of the anime, it is revealed that Koga united all of the wolf demon tribes and married Ayame, the wolf demon girl he had long ago promised to marry "on the night of the lunar rainbow" (A promise he had seemingly completely forgotten when she appeared earlier, but evidently eventually decided to keep). In the Final Act, he and Ayame marry.
In the anime adaptation, he is voiced by Taiki Matsuno. In the English dub, he is voiced by Scott McNeil.