lol Back on the metal are we? Since none of us are experts, this would all be purely entertainment and an indulgence of our nerdiness. 

I'm gonna go with the bullet had to impact the blade at the right angle to ping off it and not shatter it. I agree that Tungsten would most likely shatter. It is also heavy. Mithias has some kinda titanium alloy. Now an "alloy" can be a mix of whatever, so I'll just say it's optimized for its purpose, obviously. 

And swords sing if they vibrate, I think any metal does. 

As for the ancient longsword/katana/etc., idk about those. I know the Samurai folded their metal like hundreds of times to line up all the molecules and stuff. Maybe the strength is from the working and not from the material?