... Razor didn't steal any code from UO Extreme. I don't even think the UO Extreme code was available when Razor was written. And Razor is in a different programming language.
UO Extreme had the ability to display the number of HP that someone had, because of a flaw in the UO servers at the time. Origin patched that, probably in like 2000 or 2001, so that all you could get was percentage. I did experiment with it, but it's too spammy to have the numbers all over your screen. Just pull up their health bar.