The story in Exodus 4 is one of the weirdest in the Bible. It's called the Bridegroom of Blood story, and Dr. Carmen Joy Imes helps unlock the meaning and purpose of this story.
I'd love to know your thoughts on other interpretations where it's about Zipporah saying to Moses that he is a bridegroom of blood meaning that she is unhappy with what she just had to do. The 'Got Questions' website has a very different interpretation.
The book of Jubilees actually has the best interpretation of these events. Mastema tried to kill Moses and the Angel of the Presence saves him (Jubilees 48:2-4)