Dueling Shield is a Thrusting Shield in Elden Ring. It is a brand new Thrusting Shield in the Shadow of the Erdtree DLC. The Dueling Shield scales primarily with Strength and Dexterity and is a good Weapon for experiencing the new weapon type added with Shadow of the Erdtree.
The Dueling Shield weapon can be found at the following location: Shadow Keep: From the middle area, take the set of stairs to the next floor. Move to the eastern side, climb the wooden platform, and fight the Vulgar Militiamen. Use the stone platforms to reach the other side, the item is against the wall. [Elden Ring Shadow of the Erdtree Interactive Map] [Video Location]
Weapon Skill: Shield Strike
This weapon can be infused and buffed. For most purposes, this shield is considered by the game to be a weapon rather than a shield.
Dueling Shield can be upgraded by using Smithing Stones
Despite being a kind of shield, many ashes of war not usually applicable to shields can be applied to the Dueling Shield.
Other notes and player tips go here

Attack
Guard
Scaling
Requires
Skills: Shield Strike
Damage Type: Standard/Pierce
FP Cost: FP -
Weight: Wgt. 9.0
"A "thrusting shield," or combined weapon and shield. Enables the wielder to attack and guard simultaneously. An armament once used in ritual combat performed to honor the Erdtree—a custom that had somehow remained within the realm of shadow. "