Just recently I was in a conversation with a number of UK mainlanders and we had a debate over what “tories” meant, apparently disproportionately ordinarily it refers to a political party and it’s not usual to use it as short for “territories” as I’ve used it (according to how the debate ended, it was half and half between them). And once again I’m reminded of how people feel to look back at their usage of a word/phrase over the years and cringe.
More tragically, me and a friend were embarrassed once upon realizing everyone was confusing “encephalitis” with “hydrocephalus” when talking to someone about their kid with hydrocephalus. Awkward because encephalitis is caused by HIV.
I would say it means strong but with an implied sadness, but you can have positive poignant memories too - you’d just have to state they were positive. The day I graduated from University was poignant because it was the end of an era and the start of another, but it doesn’t mean it is a sad memory.