There are two knights jousting and each has a clock. Let's assume they want to move their weapons in the striking position just before the strike. so if they do a dry run to see at what time they need to strike and then agree that they are gonna aim only when the clock shows this particular time, what will happen when they joust for real?

As I understand Einsteins relativity, from the perspective of each knight the other one should have a late moving clock (assuming they synchronized them before) and therefore each one should be able to pull the strike while the other is way too late for it, so each knight be victorious from his own perspective. But that is a contradiction. How to explain this?