A Guthix godsword is a extremely strong weapon hitting up to 450. To get one you have to have a visage, Armadyl godsword, Saradomin godsword, Zamorak godsword, Bandos godsword, Guthix blade 1, Guthix chain, and a flaming grassbow. With a smithing level of 70 you can create a guthix godsword. Since it costs 145,063,891 coins to make (250,000,000 buying stuff for it), you can also get it as an extremely rare drop from an Imperial demon. It is also useful for the Belly of the Beast quest.