1. There is nothing in game which indicates that you should catch the energy bursts on your sword.
2. There is nothing in game which indicates that the energy bursts will break the shield, it's a new mechanic.

• I'd love to see a lower tech entry to that mechanic to gain entry to the tower in the first place. That would create the impression of a consistant magical techniques. Maybe something which looks like a weaker version of the top shield.

-Similarly a triangular shield which is broken by those skull attackers being something which occurs out in the world by mobs could introduce the mechanic.

3. The energy bursts cannot be told apart if you are blue green color blind, suggest changing one of those colors to something which can be identified as such, maybe imbedding a symbol.

That said, this was an amazing fight, it took me over an hour of play, and wrecked two sets of armor, my wight's bane, and ran me through all of my food and sap which I had looted from the tower, which is probably a bit much for most people.