Want a protip? You should always make damage to the adds (in this case the gugnir swords), raise people if you're able to (yes this counts as participation). And then at the same time deal damage to the boss. Might help you get a gold medal? I haven't had many chances to participate but I've noticed from other fates that it's easier to target and damage multiple things to get a chance for a gold medal, should work with this fight as well.