I'd say the most used term for all of those situations is 'blunt'. 'Dull' has been used for knives which needs to be sharpened but it's not heard much these days. In fact, if somebody told me the knives were dull, I might think they needed to be polished - they aren't shiny.

I’m curious how others will reply, but I wouldn’t use ‘blunt’ for any knife, even if it were dull. I hear ‘blunt’ as either ‘blunt object’ or figuratively to describe communication.