I think there was some misunderstanding in this thread, I think the original poster had more to do with helping his friends yet alot of you here took it wrong. He made what he intended to be an informative yet entertaining comment to his buddies about their poorly made knives to either help them better appreciate knives or at least get them to think about it somewhere down the line, if they ended up doing neither then hey, it was just a joke! so don't get the shorts knotted!
and these knives ... a poorly made knife can actually cut quite a swath, until it doesn't or until it presents a safety issue which may or may not be obvious, so he tried to also assist them in the way of being safe. His "joke" may or may not have been intended to be directly understood, overall he seemed to be just trying to get them to think. Example if someone told me that's not a knife back before I knew much about knives I would think wtf is this guy saying?? but I would not quickly be insulted until I knew what the intended point really was, and maybe the OP has buds who will wait to find out what it is he is saying, before they get offended, ... it depends on the situation, how well you trust or know the person and how the point is being communicated, as in tone, setting, and so forth. In other words "The truth is not simply what you think it is, it is the circumstances under which it is said, to who, why and how it is said" [Vaclav Havel].
All that "being said" I do realize that one can take a comment as an insult, hopefully the one making the comment has the social acumen to make it clear at the time that no insult is being intended, of which acumen I do believe the OP does have, it just failed to be extrapolated as such in this thread by other forumites.
The verdict on the OP: NOT GUILTY, ...he is calling BS and quite rightly so and I support him in that 100%.