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.