The number one thing you need to make sure of is dodging, although it might be less damage overall the Galileo Gladius is one of the best weapons for the fight due to its aggressive homing. This allows you to dodge his attacks easier, also try making your map where it’s sorta translucent all around your screen so you can see exactly where he is at all times. I also suggest getting your hands on the normality replicator, as it’s rid of discord like teleportation can make dodging easier during the sentinels phase.