That's the DMT. What I'm talking about is completely different.

Recently hampa added a function to the game that allows you to see the damage a joint took during a hit by typing /dm 1 and hovering the cursor over said joint (kinda faulty, but it's a new feature).

There aren't really many people who know about it and I doubt there's anyone who uses it, that's why I didn't have high hopes for an answer.