"Secret weapons" is a common phrase used to refer to something that is unknown or untested that can provide a competitive advantage. However, there are several synonyms to use for this phrase that can enhance your writing. One of them is "hidden assets," which involves utilizing resources or abilities that are not immediately apparent. "Ace up your sleeve" is another synonym used to describe an unknown or unexpected resource, while "game-changer" is an idiom referring to a significant change that alters the outcome of a situation. "Trick up your sleeve" is an expression that emphasizes surprise or deceit, and "wild card" implies an unpredictable and potentially advantageous factor. Using these synonyms can help spice up your writing and express ideas more clearly.