I think you answered the question without realizing it.
1. Faith is assurance, Not confidence, I can have confidence someone can do something, It does not mean I have faith he will succeed.
Example's
1. Abraham had so much faith, he KNEW or as scripture said, he was Assured God would keep his promise, thus he offered his son as a sacrifice, Knowing (assurance) God would raise him from the dead.
2. Noah had so much faith, He KNEW as scripture said, God would flood the earth, He KNEW and was assured, the ark God told him to build would save him and his family, and he was assured (not just confident) that God would do everything he said he would do. So he endured, and built the ark.
I agree, God asked Peter 3 times if he loved him, And even though peter could only say I love you (lower Philip, not the deep Agape) Jesus still told peter.. Thats ok, Feed my people.. Peter, in the spur of the moment lost faith.. It does not mean he lost salvation, or that his faith was dead..