Whale skin is not doing anything, even if you have no armor when you collect a star you get nothing.
Just finished my Star Knight run, it was the most unfun class I have played so far. Many of the artifacts should be default for the class, like not losing the whole combo upon failing to get a star or having the stars only landing 2 tiles away instead of 3
Starlight Injector also seems to not be working, it only seems to trigger with the basic defense card and it does not preserves the combo, so it is basically useless.
I have a few suggestions to improve the class and make it more reliable:

-Make the stars only land a max of 2 tiles away
-When you absorb a star you gain +5 armor and +1 spikes
-If a star is not absorbed and expires it becomes a spark that deals 2 damage to the nearest enemy

In the early/mid game you don't get enough armor, nor deal enough damage, the class is fine on late game after you get basically every artifact, but then the game is already over.