I'm Not A Knife Expert - Tumblr Posts
What the knife (might) be

I love the website and all, but this subtle rainbow effect on the knife/sword/dagger thing is annoying me. I'm by no means a knife expert but I have a couple theories as to how this blade could be getting this effect.
Maybe it's heat colored titanium?

Heat colored titanium usually looks something like the picture above, which lines up ok with the knife in the website, but it has a lot of drawbacks for a practical knife.
Titanium knives don't hold a long lasting cutting edge, and are much more brittle than steel, making it not the best blade for cutting. Which (as the blood + being stabbed into the book) shows that it's not that likely to be titanium.
It might have a neochrome coating?

Neochrome coatings are usually used for cars and car parts, but it is pretty commonly used on knives and silverware.

The problem with the neochrome possibility is that most neochrome knives are a lot less subtle as the one on the website, so I think it's a lot less likely that it's a neochrome coating.
It's a knife finish?

The last possibility I thought of was that it's just an extremely reflective knife finish (maybe a mirror finish?) and it's reflecting light from the room.
This seems the most plausible, but I'm probably gonna stick to the thought that it's titanium bc I personally love how heat treated titanium looks.