The phrase "come in handy" is commonly used to express the usefulness of something at a particular moment or situation. However, there are alternative synonyms that can be used instead to express the same sentiment. Some of these synonyms include "prove useful," "serve a purpose," "be advantageous," "be beneficial," "be of help," "be of use," and "be convenient." These alternatives can help to add variety and depth to the language used in writing or speaking and can make one's expression of ideas more interesting and engaging. Ultimately, the choice of synonym to use would depend on the context and tone of the message being conveyed.