Very interesting OP coin, this fractional dirhem of Tancred. My standard work by Alberto D'Andrea (short 'DA') mentions a silver percentage of 7-25%, it is DA 405. I have DA 406, another small coin of Tancred where he presented himself together with his son and crown prince Roger (+ ROGERIVS REX). It was minted in Messina in 1192-1193.