Pistol Kanji
From Halopedia, the Halo wiki
Stamped onto Halo: Combat Evolved's M6D Pistol are two Japanese and Chinese character: The Kanji and Seven characters that can be seen only with the aid of a scoped weapon, such as the Sniper Rifle.
The first Kanji, stamped onto the top of the ejection port, is 七, shichi/nana (jp), or qi (ch) and, when translated, is the number seven.
The second Kanji is found on the bottom of the magazine floor plate, and is the character 力, chikara(jp) or li (ch). Meaning "strength" or "power", it is not surprising considering how powerful of a weapon the M6D is.