Epee is unique of the three weapons in that it does not have a designated target, and does not have the concept of right of way. This makes it both the simplest of the three weapons to understand and the slowest to watch.
The main reason for this is in those two unique aspects:
The entire body is target: You will see wrist hits, toe hits, if the tip hits any part of the fencers body it is a touch.
Whomever hits first gets the touch, if both fencers hit at the same time, they both are awarded a touch: This means that you need to create an opportunity to hit your opponent without allowing yourself to be hit.
Strategy, timing and perfect technical execution of an action are keys to success in epee. Because both fencers are playing a very strategic game with no room for error, the bouts can appear to move very slowly.