Possible Clues:

• Ancient critical printing marks
• Former pupil, the Spanish one, making signs with a dagger
• Dagger signs from old boy with old priest
• Nigerian tribesmen hold up the French with daggers drawn
• Manuscript marks noting possible errors
• Printers' marks; be oil (anag.)
• Daggers sheathed in Nobel Institute
• Rebellious Gaul's broken end off daggers
• Some uplifting worthwhile boycott of daggers
• Wardrobe likely to conceal daggers