You can't farm this weapon without being a complete grindhead.
Tips
culture
肝 (liver) is gamer slang for 'grind' (staying up late damages your liver in Chinese folk belief). 帝 (emperor) marks someone exceptional at it. Cf. 氪帝 (whale king) for heavy spenders.
register
Gaming slang, mildly admiring or teasing. Often self-applied: 我今天肝了五小时 = 'I grinded for five hours today'.