The problem is that some of those who - voluntarily or unvoluntarily - abstain form the forum now, usually make very good contributions and their participation is part of the value of this forum. Banning them from the forum means cutting off the foot in order to get rid of a blister.
In my eyes, the easiest way would just be: to let go on those who like to make - good or bad or amibiguous - jokes, or even personal attacks. After a few days they will be bored, and their "discussion" thread will be read only by themselves anyway - and maybe by a few people who are feeling so bored that even name calling seems interesting to them.
If some of those feeling attacked in a discussion thread complains, delete the complete thread with a remark in the forum such as "deleted on request of N.N."
I think whether a joke or ironic/sarcastic remark is an insult or not, or worth a reaction or not, is basically a matter of personal taste. Why involve in making such judgements ? Some people are more thin-skinned than others.
That's just my personal opinion, of course. I won't protest against any decisions you take. It is your forum, so you make (and have to make) the rules. And I am happy it exists, even though I would be happier if it existed without banning people.