I wrote this up a while back and it's mainly geared toward D20 Modern but I think it should be easy to convert to other d20 games or just take the fluff and add it to any system.

Spear of Destiny
Description: The Spear of Destiny is an ancient weapon. Forged near the beginning of time it has seen more battles and death than any other weapon in existence. Its most famous application was the piercing of Christ’s side by the centurion Longinus. From this singular event the Spear was cursed; anybody wielding the spear was destined to violent and bloody end, usually with its loss. The Spear was lost until found by the Roman Emperor Constantine. With this mighty artefact in hand he conquered great swaths of land for the empire, and converted to Christianity.
The Spear appears sporadically throughout history in the hands of Charlemagne, or being sought after by the likes of Napoleon. The Spear eventually fell into the hands of the Hapsburgs, rulers of Austria, and remained in the country until the beginning of the Second World War. When Hitler invaded Austria he took the spear with him to Nuremberg, feeling that it would give him the power needed to conquer the world. When General George S. Patton captured Nuremberg, and in turn the Spear, Hitler committed suicide. The Spear was returned to Austria and there it still resides, or so it is assumed.
Powers: The Spear of Destiny acts a +5 keen defending wounding shortspear. The spear also gives the character the Leadership feat, as well as a +4 enhancement bonus to Charisma while in the character’s possession. The Spear also has a powerful curse: should the current owner ever lose possession of it (this does not include intentionally setting the weapon aside), he suffers 4d6 points of Constitution drain (Fort DC 30 for half). PDC: - RES:-

The Bowie Knife of Quincey Morris
Quincey Morris was a Texan, an American tried and true. Not to mention he was a very wealthy man. His journeys eventually took him to england where he met the beautiful Lucy Westenra, and became one of her many suitors. Lucy was suddenly stricken with a strange ailment wich eventually turned her into one of the living dead. After a bit of detective work, and a long chase into the Carpathians Mountains into Transylvania, Quincey lost his life defeating the legendary vampire Dracula by stabbing him the heart. Quincey's final sacrifice imbued his knofe with magical, supernatural powers.

The knife appears as an antique Bowie Knife still sharp to the touch, but with a bit of dried blood that seems not to want to be washed off. The Knife functions as a regular knife with a +2 magical bonus attached to it, but its true power shines when used against a vampire.
When used against a vampire, the bonus increases to a +5 enchantment bonus. A vampire hit with the knife must make a fortitude save or be affected as if the vampire has been hit with direct sunlight. This power is in effect as long as the vampire is within 30 ft of the knife. However, if a vampire should be hit with the dagger, and moves 30ft away before anypermanent damage, i.e. death, occur, she is unaffected by this power for 1D6 hours.
The Bowie Knife may also be used to bless a place or a residence froma vampires intrusion. If the knife is used to draw a line in any doorway, window, or is used to draw a circle around a person or object, a vampire may not cross this line. If the controller, or a friendly charector attempts to make an attack through the barrier against a vampire, the line is considered broken, and its effects nullified. Attempts made to use the Bowie Knife to trun a vampire receive a +4 circumstance bonus.
Purchase D.C.: 36

"How I did It" - The Diary of Victor Frankenstein
This nondescript tome, contains the processes Victor Frankenstein used to create life from the parts of the dead.
There are 2 known versions of the book floating about, one owned by Desdinova Arkham (Billionaire industrialist & Owner of Northwind Tech) and a handwritten copy is owned by the Francesican Order, located in the swiss alps.
Purchase D.C. : 35 for original or 25 for incomplete copy
skill bonuses +2 to heal checks

The Ethereal Radio:
This bizzare 1920's style radio was rumored to have once been owned by Allister Crowley.

Cryptic designs and pentagrams decorate it's black wood frame. Tuning it allows one to use the radio to "Speak with Dead" (6th level caster) once per day.
The radio must be placed within 2 feet of the deceased to gain the effect.

The Skull of The Headless Horseman

The Headless Horseman was a Soldier that lost his head in the revolutionary war due to one reason or the other. It is not exactly known for sure how, or why it was removed. Rumours are abound of anything from a decapitation, or The horseman being in front of a cannon as it was fired. Given the state of the skull, decapitation seems more likely.
The skulls of The Headless Horseman appears as an average worn, discolered, fleshless skull with the lower jaw and several teeth missing. Once per night, and only at night, the owner of the skull can call upon The Horseman to attack the person of the users choice, not resting until he dismembers the persons head, at wich point he retrieves the head, flees any remaining combatants, and returns the head to the posessor of the skull. The Horseman cannot be called upon to take another victim as long as a victim he has been sent after still lives. If The headless Horseman should happen to "see" his skull, he attacks the person weilding it trying to sever their head, on a success he retrieves ghis own head, and returns to his unmarked hidden grave. Treat the Horseman as a level four strong hero with the corpse creature template from the Book of Vile Darkness except as follows: Although the Horseoman is headless, he can still see and hear normally, although he cannot speak. He understands English and one other European language. His allegience is only to the owner of his skull. His only posessions are a hand axe, and a vorpal longsword, and a set of black studded leather armour. His horse is treated as a heavy war horse with the corpse creature template on it. Niehter the Horseman, nor his mount may enter hallowed ground, be it a churchyard, magically blessed area, or otherwise.
If the skull is returned willingly or other wise to the Horseman, he immediately returns to his grave.
Purchase D.C. : 30
Wyatt Earp's Colt SAA (Single Action Army .45 revolver)

The famous Colt .45 used by Wyatt Earp (and other lawmen of the old west), this particular Colt is based on a Mastercraft frame, with classy sandalwood grips. The weapon has a bonus vs Chaos Aligned entities, and is deadly in the hands of even a novice shooter. The years of legend and the rise of Shadow have attributed magic properties to this weapon.

Type- Colt SAA +3
Damage- 2d6+3 (+2d6 vs Chaos Aligned Creatures)
Critical- 20 x2
Type: Ballistic
Range- 30 ft
Rate- S
Ammo- 6 cyl. (.45 caliber)
Size- Small
Weight- 2.5 lbs (actual 2.65 lbs)
Purchase DC- 35+
Restriction: Licensed, Rare (magic)

I know almost nothing about d20 modern. I played a bit, but never more than a few nights' worth for each campaign, and only a few campaigns. I didn't even realize they had magic/special items lol.