Glass sword

A glass sword is a magical blade of nigh unsurpassed power, which is made out of specially prepared glass. While it may kill virtually any being it strikes dead with a single well placed hit, it will always shatter upon impact, making it a weapon to be used cautiously. Such swords appear in  Ultima V,  VI,  VII,  VII Part Two, and  IX.

Age of Enlightenment
Glass swords first came into use during the time of Lord Blackthorn's reign. During this era, a number of them were manufactured by an unknown craftsman before being lost deep within the Serpent's Spine by an airship captain transporting them. By speaking to the glassblower, Sven, the Avatar could learn of this hidden cache of crystalline blades, and could potentially retrieve them to assist in toppling the oppressive regime of the age.

Over time, such swords became slightly more commonplace items, and could be found on occasion amidst caches of treasure. During the years of the Gargish conflict, the Avatar was tasked with retrieving a glass sword for the astronomer Ephemerides, who required one as a structural foundation in fulfilling the hero's request for a concave Codex lens. Minoxian glassworker Dale was able to craft such weapons on commission, but would require a number of peer gems in order to create these mystical blades.

Age of Armageddon
Although glass swords were still present in Britannia centuries later, the art of their manufacture appeared to have been lost to the weaponsmiths of the realm; on distant Serpent Isle, however, the denizens of Moonshade still appeared to be well versed in their construction, and would freely sell them for a hefty fee.

In  Ultima VII, glass swords are rated as having and effectiveness of 127, and in the  Ultima VII Part Two, they are listed as having a damage of 127 and a reach of 2. In  Ultima IX glass swords do exactly 500 damage per hit.

Ultima V
Glass swords may be found at the following locations in Ultima V:
 * Serpent's Spine.

Ultima VI
Glass swords may be found at the following locations in Ultima VI:
 * Buccaneer's Cave, in a chest on the second level.
 * The lower levels of the sewers beneath Castle Britannia, in possession of Phoenix. One in each hand and one can be found in her backpack.
 * Bonn's cellar on Dagger Isle.
 * In the dungeon Destard.
 * Minoc (Sold by Dale for five peer gems)
 * In a magically locked chest in Sutek's catacombs.
 * Deep within the catacombs of Moonglow.

Ultima VII
Glass swords may be found at the following locations in Ultima VII:
 * Cape of Heroes.
 * In the dungeon Deceit at 25N/178E.
 * Dragon Treasure on the Isle of the Avatar at 161S/191E.
 * Two of them are at the Guardian's "X" on 48N/137E.
 * There are four of them in the Pirate treasure at 169S/28E.
 * In the dungeon Shame at 21S/43W.
 * A big number of these can be found on a corpse in the secret room of the Test of Love on the Isle of Fire.

Ultima VII Part Two
Glass swords may be found at the following locations in Ultima VII Part Two:
 * Hazard's Camp.
 * Moonshade (Sold by Pothos for 1500 guilders)
 * Moonshade, in the store room of Pothos.
 * Numerous of these can be stolen from the fake Dupre in the test of purity. Attack when only one worm is left, the use Vibrate numerous times, later escape by picking the lock.

Ultima IX
Glass swords may be found at the following locations in Ultima IX:
 * Well in Britain, throw in coin from the bench to make sword appear.
 * Treasure chamber of Queen Zhah in Ambrosia.
 * Secret shop maze in Moonglow.
 * Found in a cave in the crystal mountains south of Yew at 7°43"S, 26°59"W.
 * In a case in the guild shop of Buccaneer's Den.
 * From the giant Creeper Plant on the plane of earth in the Abyss.
 * Secret room in Terfin off the long way south after the jail cell room.

Trivia

 * In Ultima VI, glass swords can be used to destroy doors, although sometimes more than one strike (and therefore more than one sword) is required.