Related Clues:

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