Thanks for such a detailed review!
Yes, after the implementation I also thought about making brute-forcing harder and the logical choices easier.
And you’re right — the key was the first idea.
Viewing post in Forge of Time jam comments
The sword is built from several elements. The mask controls the border shape. The shape itself is achieved by applying a height map to a flat color with a simple light source. The height map is always the same — it doesn’t depend on the border shape. When the sword is motionless, the shape is cached and only the mask changes. When it moves, the height map is applied every frame.