The Collaborative International Dictionary
Bloody hand \Blood"y hand`\
A hand stained with the blood of a deer, which, in the old forest laws of England, was sufficient evidence of a man's trespass in the forest against venison.
--Jacob.(Her.) A red hand, as in the arms of Ulster, which is now the distinguishing mark of a baronet of the United Kingdom.
Wikipedia
Under the old English forest laws, bloody hand was one of the four kinds of trespasses in the royal forest, by which the offender, being apprehended and found with his hands or other body part stained with blood, is judged to have killed the deer, even though he was not found hunting or chasing.
Usage examples of "bloody hand".
I grasped the handle of the machete with my bloody hand and began using the blade to sprinkle blood as I walked.
Hugh did so, unwrapping the leather thong from John Darby's bloody hand.
Even as the next bomber straightened out on its strafing run, even as he flung himself backwards, Turner saw the mangled, bloody hand reach out for the trigger grip again.
When Arya turned, Lord Beric Dondarrion was standing behind her, his bloody hand clutching Thoros by the shoulder.
Before he realised it, his bloody hand and the knife had dropped into the sea with a dull plop.