EDGE n. 11 definitions
The thin cutting side of the blade of an instrument; as, the edge of an ax, knife, sword, or scythe. Hence, figuratively, that which cuts as an edge does, or wounds deeply, etc. He which hath the sharp sword with two edges. Rev. ii. 12. Slander, Whose edge is sharper than the sword. Shak.
DREDGE v. 5 definitions
To catch or gather with a dredge; to deepen with a dredging machine. R. Carew. Dredging machine, a machine (commonly on a boat) used to scoop up mud, gravel, or obstructions from the bottom of rivers, docks, etc., so as to deepen them.