Since I knew in advance that I would be able to supply my runners with equpiment, I saved a lot of good armour and weapons for this purpose (they were a pain hauling around, taking up space in my inventory, but hey, what don't you do to prevent union trouble?)
However, when I got my tower - only yesterday, in fact - I found that the way to outfit my runners was to pay my enchanter and trainer in gold to supply equipment. A basic set of armour and a basic weapon costs 1000 gold apiece, for every runner. So to outfit all three of them with basic equipment would cost 6000 gold, if I do the math correctly. Presumably, there is an option to upgrade.
If there is a way for the Dragon Knight to give the runners any special equipment from his or her own stash, I haven't found it yet.
