Hammers in Elden Ring: Nightreign are blunt weapons that deal excellent poise damage and are particularly effective against certain undead enemies and armored foes. Their smaller size and solid stagger capabilities make them great for fights in tight spaces, though their range and speed are inferior to swords. They are great for builds that focus on poise breaking enemies, if you don't want to sacrifice much of swing speed.
NightreignHammers - Nightreign Wiki

Club
Hammer • Lvl Required 1
Weapon Skill: Barbaric Roar
Let loose a bestial roar to rally the spirit and increase attack power. While active, strong attacks change to savage combo attacks
A thick, solid lump of wood. Wielding this striking weapon requires no skill. A simple, primitive weapon that requires only brute strength and persistence to hammer your foe into the ground.

Curved Club
Hammer • Lvl Required 1
Weapon Skill: Barbaric Roar
Let loose a bestial roar to rally the spirit and increase attack power. While active, strong attacks change to savage combo attacks
Hard, curved club, shaped like a crescent moon. Wielded instead of a curved sword by Albinaurics lacking dexterity. The only point of similarity between the two is the shape.

Envoy's Horn
Hammer • Lvl Required 7
Weapon Skill: Oracular Bubble
Blow on the horn to release a magic bubble. The bubble floats gently through the air towards its target.
Golden horn of the Oracle Envoys. Profoundly weighty, its blows are sure to be felt. Originally an instrument, but one that cannot be sounded by a mere human. Or perhaps it is too early to sound the call.

Hammer
Hammer • Lvl Required 3
Weapon Skill: Kick
Push an enemy back with a high kick. Effective against enemies who are guarding, and can break a foe's stance. Sometimes a simple tool is the most effective.
Hammer comprised of a large stone affixed to a metal handle. Originally a blacksmith's tool. The art of smithing is said to have originated among the giants. This weapon's striking attacks boast ample weight behind them.

Mace
Hammer • Lvl Required 1
Weapon Skill: Kick
Push an enemy back with a high kick. Effective against enemies who are guarding, and can break a foe's stance. Sometimes a simple tool is the most effective.
An iron bludgeon with sharp protrusions. Striking attacks have few drawbacks, potent as they are at breaking through guards and stances, Most suited to head on slugging matches.

Marika's Hammer
Hammer • Lvl Required 10
Weapon Skill: Gold Breaker
Leap up high and, while suspended in midair, imbue the rune shard with light before smashing it down hard onto the ground. The heroic Radagon's signature attack.
Unique Weapon Passive: Power of the Queen
Stone hammer made in the lands of the Numen, outside the Lands Between. The tool with which Queen Marika shattered the Elden Ring and Radagon attempted to repair it. The hammer partially broke upon shattering the Ring, becoming splintered with rune fragments.

Monk's Flamemace
Hammer • Lvl Required 3
Weapon Skill: Kick
Push an enemy back with a high kick. Effective against enemies who are guarding, and can break a foe's stance. Sometimes a simple tool is the most effective.
Battle hammer made to resemble flickering flames. Signature weapon of the Fire Monks, who hail from the Mountaintops of the Giants. The unique strong attack rouses fiery combative spirit.

Morning Star
Hammer • Lvl Required 3
Weapon Skill: Kick
Push an enemy back with a high kick. Effective against enemies who are guarding, and can break a foe's stance. Sometimes a simple tool is the most effective.
Battle hammer comprised of a globe attached to a handle. Though a bludgeon dealing strike damage, the appellative star is covered in spikes which cause blood loss. Ironic given its graceful name, this weapon often reeks of blood.

Nox Flowing Hammer
Hammer • Lvl Required 7
Mace shaped like a suspended metal droplet wielded by monks of the Eternal City. Forged from liquid metal from a Silver Tear, it is thoroughly tempered until hardened.

Ringed Finger
Hammer • Lvl Required 7
Weapon Skill: Claw Flick
Cause the finger to swell, then flex to build up strength before giving enemies an almighty flick.
Bludgeon made of an enormous finger sheathed in several heavy rings. Thought to have been cut from an ancestor of the Fingercreeper. Some life yet remains in this legacy of an ancient act of blasphemy, as evidenced by the barely perceptible warmth it still exudes.

Scepter Of The All-knowing
Hammer • Lvl Required 7
Weapon Skill: Knowledge Above All
Raise the scepter to manifest the realm of the All-Knowing. Enemy magic and holy damage negation will be reduced for all within the area, including the caster.
Scepter in the form of a hand grasping a pearl. Signature weapon of Sir Gideon Ofnir, the All-Knowing. The pearl stands for the world, the heavens, and an eye, representing the many forms of knowledge, never fully attainable. Even knowing that, the All-Knowing's hand grasps for it.

Spiked Club
Hammer • Lvl Required 3
Weapon Skill: Barbaric Roar
Let loose a bestial roar to rally the spirit and increase attack power. While active, strong attacks change to savage combo attacks
A club with beast fangs wrapped around the striking end. The uneven spread of fangs causes blood loss. Given only to the toughest of demi-humans, this weapon is a badge of honor. Or so the demi-humans believe.