Foible is a noun that means a minor shortcoming is someone's character.
In fencing, the word forte refers to the strongest point of the blade. So understandably, forte became a word to describe a person’s strongest skill or characteristic, as in: Jeff’s forte is public speaking. That’s why he’s done so well performing lectures at college.
By contrast, the foible (derived from the Old French word for ‘feeble.’) is the weakest part of the blade. And Foible refers to the person's weakest trait or skill. I don’t know why Mable insists on doing a dance routine for the talent show. Everybody knows dancing is her foible.