I've never regretted giving away the Dark Star or the Leopard Cub...nor selling the balisong. The Cub went to the son of an LEO I know online as his first "real" knife. The Dark Star was a gift to a forum member for having given me a couple of good deals I appreciated. And the balisong, I couldn't resist the offer.
Life's too short to worry about it...but yeah, there are quite a few knives I'll never part with.
As an example, the AFCK was co-designed by Chris Caracci. (I didn't know it when I picked mine up.) But Chris was my primary instructor at my first SWAT school back in the late 80's or so. So, there's a lot of personal meaning with that knife as I carried mine on the job quite a bit back then.