Context: a girl fights a beast-man lion, the king of animals.
{ou ni idomu} kotono oroka-sa to kyoufu φ sono mi ni kizame 王に挑む事の愚かさと恐怖その身に刻め Carve into [your] body the foolishness and fear of [the act that is] to challenge the king.
i.e. it was a pretty stupid thing to do, hopefully getting beaten to a pulp will help you remember that.
{ou ni idomu} koto 王に挑む事 A thing [which is] {to challenge the king}. [The act that is] of challenge the king. The act of challenging the king.
umarete kono kata doumo sono {kyoufu tte} yatsu wo shiranakute ne 生まれてこの方どうもその恐怖って奴を知らなくてね Since I was born, for some reason I've never know that "fear" you're talking about.
umarete kono kata 生まれてこの方 Born, this person. Since this person was born. (he has never.) Since I was born. (I've never.)
doumo どうも Anyhow. In one way or another. For some reason. (for some "how," for some "way," which the speaker doesn't know.)
sono kyoufu tte yatsu その恐怖って奴 That "fear"-called thing. That thing [someone] called "fear." That "fear" thing [you mentioned].
