Socksniffer
Maybe the myth class sigils if I remember right they had to have god in Their name. Maybe god of thieves ( can steal items and finds out later can steal powers) plus he goes to overlord later on and then tensura because that world upgrade skills etc. if he gets a animal rank sigil can go for a skin walker they can turn into anybody and animals technically is a animal. And since he’s technically still human won’t get the negative effects that skinwalkers have like silver.
From what I've seen in the anime, I guess something like adding properties to objects like... Running shoes Add three quick speed boosts every hour. Glock 19 Add pierce effect Maybe the weakness is that they break easily since objects aren't meant to go beyond their limits, and the more powerful the properties, the easier they break. P.S. But you cannot add this weakness or change it for another, etc., but it will be cool to see this sigil, and the MC has too much plot amor in this anime. >_> But it’s not that bad of a anime so far.
Puede ser 'Mente super analitica' y 'presicion mortal' Siendo que tiene una mente que puede pensar en 100 planes en 0.5 segundos y tener presicion con cualquier cosa y nunca fallar. Son simples pero muy buenos para el prota que ya va en camino a ser un buen estratega y planificador ademas de que el ya es adaptable a las situaciones innesperadas.