To cause something to be covered with blood; to bloody.
To let blood (from); to bleed.
To initiate into warfare or a blood sport, traditionally by smearing with the blood of the first kill witnessed.
Experienced.
I'll let a rookie march behind me with a loaded weapon once he's been blooded in combat, until then he stays in front where I can see which way he's pointing.
Descended from.
He's a full-blooded Apache.
Bloody, bleeding.
(of horses, cattle, etc.) derived from ancestors of good blood; having a good pedigree.