A sea-knife is a long-handled weapon with a short blade. It is designed to be strapped to the ankle or foot of the wielder, pointing downward and jutting out beyond the wearer's leg.
Benefit: A sea-knife can be used as a light melee weapon when the wielder is swimming, flying, or prone. This allows the wielder to use a two-handed weapon, or wield a weapon with one hand and carry a shield, and still make off-hand attacks with the sea-knife. Attacks made with a sea-knife take a –2 circumstance penalty on attack rolls in addition to all other attack penalties.
Donning or removing a sea-knife is a full-round action.
Note: The wearer cannot use a leg with a sea-knife strapped to it for walking or running.