yes he should just kill the lord, after all he got a marquis ring, and if the only witsness are the lowly one it doesn't really count... The only matter is that MC is a class 5 wizard and a have a marquis ring, and there is all the mercenary and some others that will confirm the sin of the lord... I understand that Mc come from a world where killing is taboo for modern society, but he should be realist, this world is still in western age there is less way to proof that you are wrong and if you are stong, loved, intelligent, possess good and strong friend, or possess a good status in that society, then you have little worry. You just have to eradicate every bad root when it is necessary. Like here...