Love the fighters corner idea. Maybe it could include tips and tricks for how to train and what to do in the "off season". That might include making armor, getting better at fighting, general advice etc. I would say that it would be a good thing to try and include fighters who are not just knights. Obviously knights would be the meat and potatoes but there are some darn talented fighters out there with lots to share who do not have the white belt.
Perhaps a regular Heraldry segment so that folks that are new, and frankly even those of us who have been around, can get some information on devices, names, persona's etc. I think that could really help the newbs.
Another idea is perhaps a segment on "interpretive re-creation". What is that you ask? Well it could be a segment that would cover tips and ideas on how to "easily" recreate historical themes in an simple way. OR ways to improve your kit without spending a fortune. You know stuff that folks have figured out over the years that you would have loved to know.
Perhaps take input from the listeners regarding things they hate and make them into a "Things I hate". Let them take part in the bit. Could be fun.
The other thing that would be great, in my humble opinion, would be a roving reporter type of bit done from time to time at various events. Imagine the side line reporter interviewing fighters at crown or a coronet. Maybe talking to folks in merchants row and finding out what is hot and what is not at the event, in the Kingdom etc.
Okay enough of my ramblings.