Is there any way to do this? I've heard of people switching equipment from one character to another, with little to no effort whatsoever.
Due to equipment binding to the knight it is equipped to, this isn't practical. Transferring equipment would entail unbinding the equipment (which costs a lot of energy), and sending it to the other knight.
However, items like Alchemy materials and freshly made equipment (even crowns and crystal energy) can be sent to another knight (even another one of yours) through the mail system. It requires crowns to do, and it gets more expensive as you send better and more stuff, but it works.