Isaiah 54:17

Isaiah 54 is addressed to a people being restored after judgment. The promise is not that weapons are never formed, but that the ones formed will not prosper, and that every accusing tongue will be answered.

The verse ends by calling this the heritage of the servants of the Lord — it is covenant language, not a charm. Read in context, it is a statement about who has the final word, not a guarantee of an untroubled life.