Holding on at the edge is read as barely keeping control of a situation. Tradition takes it as a moment of suspense — holding on or letting go — and as a picture of how strained you feel.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.