Here is a man who slips into a house with the deliberate intention of committing murder.

He knows, if he knows anything, that he will have a deeficulty in making his escape, as the house is surrounded with water.

What weapon would he choose?
You would say the most silent in the world.

Then he could hope when the deed was done to slip quickly from the window, to wade the moat, and to get away at his leisure.

That's understandable.