As far as I know, Loricatus can only harden the copper family of metals, up to adamant. 
Something to have in mind: Loricatus can come handy even if he doesn't like you. If you are starving you can wield something heavy like a body armor and pray to him, he'll get pissed off and turn your wielded weapon into banana flesh, there you go, free food!
                                                kobold lord
                                                Ex-Tyrant of the IVANers
                            
                            
                            
        
                                                Mage Prophet
                                                angel
                                                Atavus
                            
                                                gibberling
                                                The Imperialist