The Templar is easily the HARDEST fight in the game. Normal mode in no way prepares you for hard mode. Spent 4 hours tonight failing to beat the Templar. Some things need tweaking in the fight such as the radius of his splash or the rate of fire... My team is very experience and beat him many times before we started cheesing just to save time. Tonight we just couldn't do it.
I wouldn't harp on him being harder than the other bosses though. Everybody knows bungie's answer. They'll just leave the Templar the way he is and make the rest harder...
We were a full group of 30s... Just kept getting overwhelmed