Tunc fortissimus Giton ad virilia sua admovit novaculam infestam, minatus se abscisurum tot miseriarum causam...The translation has suffered some mutilation. It omits infestam (= harmful, dangerous, modifying razor), which is Pithoeus' correction for the infertam or insertam of the manuscripts.
Then the gallant Giton turned a razor against his genitals and threatened to put an end to our troubles by self-mutilation...
There was even more mutilation in Heseltine's original 1922 translation, which cut out genitals (virilia) altogether:
Then the gallant Giton turned a razor on himself and threatened to put an end to our troubles by self-mutilation...