Here a full run down talk to Terrance until you visit the farm then get to lvl 10 sxp then visit Mjolnik and there will be a prompt at the bottom saying you need lvl 10 sxp. Note you have to be lvl 10 sxp before visiting Mjolnik unless you have to restart on a new save but on 1.04 version you don't have to restart just get to lvl 10 sxp then visit Mjolnik.