Possible Clues:

• Gladiators' weapons
• Weapons for some gladiators
• Spears with three prongs
• Spears associated with Neptune
• Forks for the sea-gods
• Neptune's weapons
• Free to enter the shelters to get the weapons
• Try to get dense, by the sound of it, with prongs
• Gladiator weapons
• With spears be rid of what's in there under canvas