I found a cheesy method that works most of the time. Don't move away from the throne. Spam the magic circle when he is outside of melee range. Use a mace attack when the magic circle prevents him from safely getting away. This works because even though he could avoid the mace by groveling at your feet, he will never actively try to do that while you are at your throne. This means he will get hit by the magic circle or the mace depending on how fast he reacts. The reason it doesn't always work is that sometimes he'll move in such ways that the magic circle is created too close to you to allow him to consider closing the distance for a sword swing.
This is rather ironic because he talks about the glory of change and lost because he is too attached the the idea of slaying you with his sword.