The Gemara says Berachot 10a
אפי' חרב חדה מונחת על צוארו של אדם אל ימנע עצמו מן הרחמים
Even if a sharp sword is resting on one's thought he shouldn't hold back from (asking for) mercy."
Why does the Gemara have to say "sharp" rather than just a sword? A sword usually makes a connotation of sharpness.