Siren Weapons

Base Features

Much like sirens themselves, a Siren weapon can manifest a variety of different mutations. When you create a siren weapon, you determine its base mutation, this mutation is always applied to the weapon. If you gain new mutations, you may spend an action to manifest the new mutation for an hour in addition to your base mutation, after which point the mutation goes away and the weapon returns to its base form.

Eel Mutation. This weapon has electricity dancing across its surface. This weapon does an additional 1d4 lightning damage.
Octopus Mutation. This weapon can bind to surfaces. Creatures grappled by you have disadvantage on checks made to break the grapple and you gain a climb speed equal to half your walking speed.
Jellyfish Mutation. - This weapon deals an additional 1d4 acid damage.
If an ability from this weapon requires a saving throw the DC is 8 + twice your proficiency bonus.

Siren weapons can be made from any Hammer or Shortsword type weapon.

Stupor Tree

Your weapon can unleash a powerful psychic blast. As an action each creature in a 30 foot cone originating from your weapon must make a an Intelligence Saving throw. A creature that fails takes 4d6 psychic damage and cannot take actions until the start of your next turn. Creatures that succeed talk half the damage and may act as normal. Once you use this ability you must complete a short rest until you use it again.

A Stupor Weapons gains an additional ability based on its type

Minor Infusion - Disruption

A Minor siren weapon gains an additional ability based it’s weapon type.

Gladus & Warhammer

Psychic Repulsion. When you are the target of an attack roll from a creature you can see, you can use your reaction to cause a burst of psychic energy to emerge from this weapon disrupting foes. The attacker has disadvantage on its attack roll.

Kopesh & Thrown Hammer

Worming Fears. Your blows cause more than physical injury. When you hit a creature with this weapon you can cause their worst fears to come to mind. The creature must make a wisdom saving throw. On a failed save they are fightened of you for one minute, they may repeat this save at the end of each of their turns ending the effect on a success. If the creature succeeds, it is frightened of you until the end of your next turn.

Maul

Stunning Blow. Your blow reverberates through a creature, the sound filling the creature to the point of pain. When you strike a creature with this weapon you may force them to make an Intelligence saving throw, if they fail they are stunned until the end of your next turn. Once you use this ability you must take a short rest before using it again.

Enchantment Tree

Your weapon emits a subconscious tone, suffusing the air around it. Creatures are unaware of this tone unless under the effects of true sight or have other magic that would allow them to detect ethereal creatures. While a creature is in this aura you may add your proficiency bonus to any checks made to persuade or deceive them. If you would already add twice your proficiency bonus to this check, you instead gain advantage.

Minor Infusion - Charm

Gladus & Warhammer.

Inspiring Presence. Whenever you or a creature that can see or hear you must make an ability check or saving throw, you may spend your reaction to allow them to roll 1d8 and add the result to that check or saving throw. You may use this a number of times per day equal to your proficiency bonus.

Kopesh & Thrown Hammer.

Fast Talker. If you spend ten or more minutes in conversation with a creature you can learn the answer to one of the following questions without the creature realizing that it imparted this information. If they cannot answer your question, you may ask another. If they fail to answer both questions you do not need to rest before using this ability again. You must complete a short rest before using this ability again.

What happened here recently?
What is about to happen?
What should I be on the lookout for?
What here is useful or valuable to me?
Who is really in control here?
What here is not what it appears to be?

Maul.

Cult of Personality. When you reduce a creature to 0 hit points but do not kill it, you may force each creature within 30 feet of you who saw the act make a charisma saving throw. A creature has advantage on the saving throw if the creature you reduced to 0 hit points is an ally of the creature making the saving throw. On a failure they are frightened or charmed by you for one minute depending on their temperament.