Hello, I wrote an answer here that you might find relevant. The TL;DR is that, essentially, 'feudalism' isn't a discrete system of government but rather an umbrella term we've projected retrospectively onto a whole complex series of inter-personal and mutually beneficial power relationships and methods of control.

In the book of Feudal Society by Marc Bloch (section named Foundation of Law), is mentioned that clergy class criticized feudal practices related customary law like bloodshed with duels, single combat etc. Hence they favoured of written laws more civilized and prevent actions unholy