(I have looked for any past suggestions on this, and could not find any surprisingly, please correct me if I am wrong)
Recently, I have thought of this as I read about Orichalcum, the mythical metal of Atlantis, and realised that the mod needs a parallel, as Numenor was theorised heavily to be based off Atantis.The men of Numenor were said to be great craftsmen, second only to the Elves and Dwarves in their craft in the Elder Days, of Eregion and Khazad-dum, thus my suggestion would incorporate a new addition to current mod items, as opposed to a system addition.
The first suggestion would be the Numernorean crafting table, which could be gained from a special Dunedain quest after one reaches 3000 Dunedain alignment. This table cannot be crafted, to symbolize the near forgotten ways of the Dunedain, and also to represent the knowledge "taught" to the player upon completion of the quest. Upon this, Numenorean weapons can be crafted.
Upon completion of a second Dunedain quest after completing the crafting table one, under the same alignment one may then recieve a Numenorean forge. This produces Numenorean steel, which is made with iron and coal in a NF (Numenorean forge). Numenorean steel can be made into 9 Numenorean dust on a Numenorean CT.
Numenorean tables/forges will have an automatic, invisible banner-like protection to them, and them only to help keep them un-usable by others on a server.
Numenorean sword
The most common of weapons, it is crafted with 2 Numenorean steel, and would be long and well crafted, like a variation of the Rivendell one. It would deal 8 points of damage.
Numenorean powder
"that pass with a noise like thunder to strike their targets many miles away"
Numenor was reputed to have many advanced, devastating weapons of old, one of which was the discovery of what appears to be a gunpowder like substance. This allowed them to make weapons very similar in description to cannon, muskets and an early form of rocket artillery, however for the sake of balance these won't be suggested. What I am suggesting however is the addition of an explosive powder, which can be used to make Numenorean bomb and Numenorean fire arrow. Numenorean powder will be made with gunpowder, Numenorean dust and Durnaur (to represent the advancements made by the influence of Sauron).
Numenorean halberd
This is to be crafted the same way as other pikes/longspears/halberds and do 8 damage. They would be long, and tipped with bright silver
Numenorean spear
This would be long, black and tipped with silver, and in essence be a shorter version of the halberd. They can be thrown for the same damage multiplier as other spears, as well as serve as a melee weapon for 7.5 damage
Numenorean armor would be mostly silver, trimmed in gold and black. It would be a less elegant set than High Elven or Galadrim armors, but far more than Gondorian ones. They would offer 17 protection points
Numenorean fire arrow
They will be made with a Numenorean steel below a Numenorean powder, a stick in the center and a feather at the back. They function similarly to termites, however they penetrate the armor and are far more lethal, dealing a heavy amount of damage any eolean player, and killing anything without eolean. They will deal the damage of the bow used to shoot it, as well as another 4 points of damage, and after 1 second, they will explode inside the armor, causing another 10 points of damage bypassing the armor completely. I intend for this to either correspond with Ithilion's Steelbow suggestion, or for them to be firable with any bow
Numenorean bomb
These are essentially orc bombs for good. They are made the same way as orc bombs, and are upgraded the same. However, they start at the same power at thrid level orc bombs, and upgrade from that, to compensate for the greater craftsmanship of the Men of Numenor, as well as to balance the insane rarity of Numenorean tables.
I do agree that this adds a potential for these to be overpowered, however I feel that good does need something to keep the balance, and also that the Dunedain have essentially nothing uniquely good to them, apart from rangers. This should even out the balance, and make gameplay far more interesting, especially on servers