Man, I wish the Masked Lumen fights were more like Alarune. She also parries and ghosts (which I don't mind in small doses), but at least all of her attacks are nicely telegraphed.
As for the regular demons that parry, I've had decent success spraying them with undine or using the hammer. Only catch is you might have to be more cautious of the timer rather than combo score.
Agreed. Humanoid bosses having invincibility frames isn't necessarily bad. Jeanne parries out of rapid attacks and has invincible dodges too. The difference between her and the Masked Lumen is that Jeanne is fair about things. Her dodge is slower and easier to follow with your eyes, and she'll pause for a moment after her parry to let you process what just happened. If you throw a Wicked Weave at Jeanne, then you know that she'll either A. get hit or B. dodge, which prevents her from attacking you for a moment. Offense is rewarded. It's actually viable to do rapid Panther Offset PKPs and Tetsuzanko's and pressure Jeanne into a corner, and the same sort of strategy can also be applied to Joy or Gracious/Glorious (two other enemies with invincibility frames).
The Masked Lumen, by comparison, will ghost out of attack (even rapid Umbran Climax punches!), then hit you immediately with fast attacks. At some point, it just gets beyond what you can expect from a human's biological reaction time, and that means that the only way to fight the Masked Lumen is by being super defensive. (This isn't helped by the fact that Bayonetta's dodge is less mobile and more easily punished in the sequel, which further discourages you from using dodging for anything besides defense.)