In The Elder Scrolls IV: Oblivion plugin Knights of the Nine Revelation there are a number of unique items, rewards, abilities and improvements that can be gained during the quests. Some of these are quite powerful, whilst others are simply unique decorative items.
Pelinal's Heart is gained during the quest The Song of Pelinal. Simply having it in your possession adds the ability Pelinal's Immortality (which gives a fairly low level heling ability). The heart also augments the powers of any equipped Relics by granting the following abilities, which work on top of the normal enchantments.
The Boots of the Crusader grant Crusader's Alacrity, which Fortifies Speed by 10 points. The Cuirass grants Crusader's Reprisal, which adds 20 points of Reflect Spell. The Gauntlets grant Crusader's Remedy, which adds 25 points of Resist Disease and 25 of Resist Poison. The Greaves grant Crusader's Fleetness which adds 50 points of Feather. The Helm, Crusader's Divination, which Fortifies Magicka by 50 points. The Shield grants Crusader's Fortitude, which adds 50 points of Resist Paralysis.
The Crusader's Mace gets the Power Attack Smite Undead on Strike and the Sword that of Lethal Cut on Strike.
Having all seven of the items equipped (all the armour and one weapon) grants an Enhanced Holy Aura, which has the standard Umaril's Bane of the normal Holy Aura, and an increase in the Shield provided to 10 points
The heart also has two powers which can be turned on or off. When it is activated in the inventory, a menu appears, allowing them to be controlled.
Pelinal's Fire causes the Mace and Sword of the Crusader to burst into flames which does additional fire damage to enemies and causes the weapon to cast light like a torch when it is drawn.
Equipping seven Crusader's Relics grants you the ability to use Pelinal's Wrath. This is an aura that weakens, slows and lowers the fire resistance of nearby enemies while healing your allies.
When enemies are hit by the aura, they sometimes appear to know that you are there, so it is not necessarily a good idea to have it activated when you are sneaking around trying to escape attention. Enemies are affected by the following effects: 25 points of Drain Agility, 25 of Drain Strength and 50 of Weakness to Fire. This affects any enemies in an area of 30 around the player. Allies who are in that area are affected by a Restore Health effect.
The Ayleids back in the First Era all have slightly magical equipment. It is all light armour and the Ayleid Boots, Bracers and Helmet all have 2 points of Shield, the Greaves have 3 and the Cuirass and Shield have 5 points. The Ayleid Sorcerer Boots, Gauntlets and Hood all have 5 points of Shield and the Robe, Shield and Skirt all have 9 points.
The Ayleid Khopesh is a one handed blade which Absorbs Magicka for 4 points for 4 seconds from the target on strike.
The Third Era Ayleids that are encountered early on in the quest series all have Dark Ayleid Equipment, which is all light armour with no enchantments on it.