I'd suggest deletion of these two. (After TRANG's suggested 2 week wait to see if there are any objections.)

Blood will have blood.
血で血を洗う。

Perhaps the other linked languages also need to be checked.

Krew krwią się zmywa.
Кровь смывается кровью.

Maybe in some languages this is a call for revenge. But in languages where these words doesn't make sense, they should be deleted indeed.

It's from Shakespeare, isn't it? Right, Macbeth. Thanks Google.

Macbeth speaks the line. In the passage he isn't calling for revenge (he is the murderer) but realizing that the dead will get revenge.

But without that larger context, I would express the meaning as something like 'violence begets violence'.

@Susan1430 is correct.
Line 122 Act III, Sc. 4:
MACBETH: "It will have blood, they say; blood will have blood."
It is indeed implying that the dead will have revenge on him. The "blood" of the dead are wanting to have the "blood" of the living because the living have wronged them. I understand that it is a weird looking phrase, but it a proverb, and a Shakespearean one at that. I think, in my humble opinion, that it is a phrase that should be kept then. "Wash blood with blood," however, could be removed, or at least changed. Same with #175716, #704017 and #2221933, as they are all translations of it. Of course, I can't force this on anyone.