Verses with the word dagger in the Old Testament (3 verses):

Judges 3:16
But Ehud made him a dagger which had two edges, of a cubit length; and he did gird it under his raiment upon his right thigh.

Judges 3:21
And Ehud put forth his left hand, and took the dagger from his right thigh, and thrust it into his belly:

Judges 3:22
And the haft also went in after the blade; and the fat closed upon the blade, so that he could not draw the dagger out of his belly; and the dirt came out.