Have you ever heard the term agency?
If not, you definitely know what it is, but you may not have realize how crucial it is to understanding the Bible.
Agency is when a messenger comes under the authority of someone else.
Think about when your supervisors brings a task that came straight from the boss. You know that the task is important because it came from the boss.
The definition of Angel is simply: messenger and many times the Bible calls angels "messengers."
Angels are messengers of Yahweh and their primary role is to relay messages from the Most High. Realize that this was understood by every single character in the Bible that was visited by an Angel. So when they spoke with Angels they often referred to them as God Himself, knowing that the message was being communicated on behalf of the Most High. Sometimes this trips people up and we get caught up in "Was it really God speaking?" when it was...but through this messenger.
When you're reading these non-canonical books, there are a lot of times when prophecies were communicated in this way, so we need to know this when we read them. Sometimes it's not an angel. It's important to stop and realize the context so we understand the story the way the characters in them did.