‘Strong suit’ is a phrase meaning a strength, something you are good at. You can easily substitute ‘strong point’ or ‘forte’.
A common mis-spelling is ‘strong suite’, which may have its roots in common terms like ‘Microsoft suite’. It is nonetheless incorrect, however tempting,
My favourite sources are unusually firmly in agreement on the origins of the phrase, and they universally state that it derives from card games, where the suits are hearts, diamonds, aces, and spades.
To be more exact, most of the etymology sources say it originated from the game of bridge. Merriam-Webster and the Online Etymology dictionary disagree on when this phrase came into use: Merriam-Webster holds it was 1742, and Etyonline says 1845. I’m going to go with some considerable time after cards came into common use and before people all got too keen on online games to play cards.
Examples of ‘strong suit’:
- Patience is not my strong suit
- He’s playing the long game; it’s his strong suit.
This seems to be a phrase that’s used in pretty much all variants of English, and it could be easily adapted for use in SFF world-building; admittedly, you would need to come up with some basic game concept to root it in first. The concept could equally easily be turned around in the world-building for a game-related phrase meaning a fatal weakness.
What is etymology, and why are you excavating it?
Etymology is like the archeology of a language (definition: the study of the origin of words and the way in which their meanings have changed throughout history).