HideousGrain
And how exactly was he able to find the butler’s strength? He told them his information instead and could be killed easily in the strength based world.
If you don't conceal your strength perfectly, others can still roughly determine how strong others are. And there is an easier way ofc; Taking a loot at the War Rune to determine tier and refinement degree. And in a world full of technology and the internet, why would you kill someone in public? For no reason at that. The Koblenheim family can easily find out Michael's information as well, so why hid it, in the first place? I hope I could answer your doubts :)