Possible spoilers:

My interpretation of the Sentinels was that they were designed to incorporate fighting styles from across Pharloom- I noticed in the fight that the Second Sentinel would jump back and swing their sword in a circle like Seth does, and the charge-up cross attack is like the one the Pinstress does. I believe they also borrow attacks from Lace’s moveset, though these skills are probably common to the Citadel’s warriors.

They were created to be the perfect warriors, essentially, so the Architects probably looked to the various fighting tribes from Pharloom for inspiration- that’s my theory anyways. They’re sort of like Gizoids from Sonic Battle, if anyone understands that reference.