Frostrazor is a powerful but obscure magical weapon from Dungeons & Dragons. This icy greatsword is essentially the embarrassing step-brother to the famous White Plume Mountain Weapons: Blackrazor, Wave and Whelm.
Unlike its more famous kin, Frostrazor was not part of the original S2 module; rather, it was added in the Advanced Dungeons & Dragons 2e module "Return to White Plume Mountain", which expanded upon the original by exploring the wilderness outside of the titular dungeon fastness. Covered on page 52 of the module, Frostrazor is part of the loot found by defeating the mad gnome fighter Saprophis, servitor of Mossmutter, a crazed and magically enhanced mold wyrm lurking in the depths of the dungeon. When Wizards of the Coast did their free "White Plume Mountain Revisted" adventure for 3.5, the requisite notes from "Return to WPM" were made into a free web enhancement, complete with converting Frostrazor into a Weapon of Legacy. Of course, with the loss of all those articles, about the only source for that web enhancement now is on DriveThruRPG.
Perhaps part of the issue with Frostrazor's obscurity may stem from the fact that its powers can be a little complicated. Frostrazor's unique schtick is that the weapon is made of a single mass of solid, jagged ice, and on a hit, there's a chance a shard will break off in the victim's body and start sucking the life from them to augment its wielder. Exactly how this worked differs from edition to edition.
In AD&D, Frostrazor is a +3 greatsword of nevermelting that inflicts 1d10+3 damage on a hit (or 3d6+3 damage on a hit vs. Large or bigger creatures). Supernaturally light for its size, it can be wielded proficiently by any creature that is less than Huge sized so long as they have at least one proficiency point in any sort of sword. On a successful hit roll of a 17+, a 6 inch long shard of ice breaks off in the wound and starts draining the energy from the victim - this has no effect on undead or "non-living" creatures like constructs. A creature can try to pull the shard out by forfeiting all actions for that turn; on a successful save vs. death magic, they manage to rip it out of their body. Otherwise, it melts away after 10 rounds of draining life essence - at least, usually. There is a 1% chance that a shard won't melt away after it's pulled out or that time is up. If that happens, there's another 1% chance it retains some of its original magic, becoming a +2 dagger of unmelting ice. Additionally, creatures killed by either the draining effect of a Frostrazor shard or just a stroke of the sword freeze solid; this means they can be shattered into pieces, just like victims of a Flesh To Stone effect, which will make it impossible to raise them from the dead.
Exactly how the Frostrazor's drain effect manifest depends on the "scoring number" of the hit - the higher the number, the deeper it was driven, and so the more life energy it can drain.A shard planted by a roll of 17 drains 1 hit point per round and transfers it to Frostrazor's wielder. On an 18, it instead transfers 3 hit points per round. On a 19, the shard instead drains 1 point of Strength every 2 rounds and transfers it, although this can't boost the wielder's Strength higher than 24. Finally, a shard planted on a roll of 20 drains 1 level or hit dice from the victim and, on the 10th round, has a 50% chance of draining a second level/hit die before it melts. Lost levels are transferred to the wielder, who gains appropriate increases in THAC0 and attacks/round.
Stolen hit points, Strength and levels can boost Frostrazor's wielder above their normal limits. However, all stolen benefits will fade after 30 minutes, although only excess (higher than max) hit points vanish.
Those who run into Frostrazor and survive will regain drained hit points and Strength at a rate of 1 per turn, but lose their levels permanently.
The AD&D version of Frostrazor is known for not being sapient, unlike Keraptis' more famous trinity of weapos. It may possibly be intelligent, but if so, it's kept its status a secret.
The 3.5 version is a different kettle of blood entirely. This version of Frostrazor wasn't created by Keraptis at all; rather, a nameless archmage crafted the blade by impaling an ancient wyrm of a white dragon with an enormous icicle stalactite, knocking it from the roof and impaling the beast through the heart before using its blood and magic to shape the icicle into a massive, crystaline blade of never-melting ice. He did this to create a superior weapon that could be used in his war against an efreet pasha. Unfortunately for him, his trusted general was actually working for said efreet, and promptly stabbed him in the back with it. Literally. After a long string of mishaps that cemented its powers, it vanished when an adventurer took it to White Plume Mountain and failed to return.
Frostrazor the Legacy Weapon is a +1 greatsword that will only allow a character with the Improved Critical (Greatsword) feat to wield it. There are three rituals you must complete in order to unlock its full power. Firstly, Piercing The Heart: kill a foe with a single blow by stabbing them through the heart with Frostrazor, then perform a 1-hour long ritual whilst the sword is still buried in their heart. Second, Bathing In The Waters of Origin: find the icy cavern where the sword was created, and then jump into the freezing waters with sword in hand. Swim around in there for an hour, come out with at least 50% of your hit points left, and it will have completed its second ritual. Finally, you must undertake the Vengeance of Garice, which requires you to find a dragon that is a direct blood descendant of the white dragon originally murdered to create Frostrazor and kill them with it. As this dragon has to be at least 800 years old to count, good luck.
Once properly empowered, Frostrazor's properties start manifesting at 5th level, when it gains the Implanted Shard ability. On a critical hit against a creature that isn't immune to such strikes, a shard breaks off and begins burrowing into their flesh, inflicting 1 point of damage per round. Digging this out requires 1 full-round action per round that the shard has been implanted. Frostrazor can only have 3 shards actively burrowing into one or more victims at a time.
Needless to say, the bulk of Frostrazor's powers stem around augmenting these ice shards.
Enfeebling Shard, gained at level 6, allows you to cast a Ray of Enfeeblement on a shard's host as a swift action 1/day (3/day after reaching level 10). Additionally, whilst the shard is implanted, a critical strike against any foe lets you zap the shard's host with another free Ray of Enfeeblement.
Wounding Shard, gained at level 15, bumps up the Implanted Shard by causing it to inflict 1 point of Constitution damage per round as well.
Life-Stealing Shard, gained at level 16, functions the same as Enfeebling Shard, but affects the host with an Enervation spell (CL10). This can be used 2/day, plus one extra time each time Frostrazor causes a critical hit.
Death Shard, the pinnacle of this trait, is gained at level 20 and works the same way as Enfeebling and Life-Stealing Shard, except now it can cast Finger Of Death (CL14) 1/day plus once per critical hit.
In addition to those powers, Frostrazor buffs itself up to being a +2 greatsword at level 7 nd then a +3 greatsword at level 12, gains the Winter Warding (Resist Energy (Cold) 1/day at CL8) power at level 8 and the Chill of the North (Ice Storm at CL12 3/day) power at level 18.
Additionally, Frostrazor doesn't adopt its true form of being made of solid ice until it hits 11th level.