Possible Clues:

• Such as Open Sesame
• Fool rejected brand name to gain entry
• Term of admission that had previously been agreed
• What's in dad's scabbard? Keep it secret
• It may have made Reeves's verse accessible
• Old man's weapon that'll secure one's access
• The old man's weapon is something guard may want
• Like to uphold power with weapon, one admits
• Father's blade which can open doors
• Eg, open sesame