They are pretty much 100% confirmed to be reskins and slight stat alterations of existing weapons. They'll likely be useless after an hour. This is basically the least scummy way to get a few extra bucks through DLC. If it helps From financially to even the smallest degree, I see very little issue with this.
"Yellow Crystal long sword and shield
Long sword with yellow crystals attached.
Found in the depths of the melted iron fortress. Though corroded and easy to break, it is light with no loss in power.
In order to show his authority, the old king built an iron castle and collected many weapons. But that glory sank into the melted earth due to his arrogance.
(shield description is the same)
Bound Hand Ax and Wood Shield
An ax with a weird appearance.
This was found in the Undead Purgatory. The chain and thorns increase bleeding but decrease slash damage.
This alteration which hides the personality of the weapon wasn't done to merely defeat an enemy. The goal was likely to simply cause more pain.
Special ability: Bleed
(shield is degraded but also causes bleed)
Pygmy's Mace and Wood Shield
A staff with round objects attached. Found in a mansion in An Diel. It is much heavier than normal but the hard spheres increase blunt damage.
To the east of Drangleig is a mysterious mansion forgotten by time. Something that should be forgotten still lurks there.
(shield is heavier but stronger)
Criminal Staff and Leather Shield
A staff with a dull black something attached. Found in an old dark hole. Used for magic and dark magic.
In places around Dranglieg are dark holes. There is yet nobody who knows what lies beyond these holes.
Special Ability: Darkness
(shield is same, just takes out part about it being used as a catalyst)
*These items have slightly different parameters from original items that appear in game.
These seem like they just took the in game item and increase one parameter slightly while decreasing another. Likely useless overall."