Related Clues:

• Gives an edge to
• Brushes up on
• Improves, as skills
• Almost trustworthy, but gets sharp
• Perfects, sharpens
• Perfects, as one's skills
• Improves, as a skill
• Polishes, as a skill
• Sharpens, as a blade
• Makes sharp again
• Almost trustworthy, gets sharp
• Gives an edge
• Works at the cutting edge?