Myrtenaster

Myrtenaster (Mur-ten-es-stur) is Weiss Schnee's signature weapon. It is a Multi Action Dust Rapier (MADR) that seems to act as a focus or source for Weiss' power.

Description
Myrtenaster is standard-sized for a rapier and primarily silver-gray in color. The hilt possesses four prongs that encase the revolver-like chamber around the ricasso, in a manner somewhat alike to a swept hilt. This mechanism can be controlled by the sword-hand, enabling her to seamlessly cycle the chamber in combat.

There are six slots in total, each of which contains a vial of Dust. The revolving chamber is constantly stocked with red, cyan, violet, white, yellow, and blue Dust. Sometimes, when Weiss utilizes the Dust in Myrtenaster, runes of the Dust's color appear on the blade, but only white and red have been shown to do this so far.

Myrtenaster is highly durable, slashing away at the Giant Armor with no visible wear on the blade. Its most prominent ability lies in the revolver-like mechanism held within the hilt, which contains various colors of Dust, activated by a trigger on the underside of one of the prongs. The mechanism can be opened on a hinge, allowing Weiss to replace empty vials. As a result, the weapon appears to have no tang.

Dust Use
Unlike many Hunters, Weiss utilizes raw Dust in combat. Her preferred method is to insert vials of Dust into Myrtenaster's revolving chamber. With a pull of the trigger, she can release Dust onto Myrtenaster's blade, or even combine Dust with her Semblance.

Myrtenaster is shown to contain yellow, blue, red, cyan, purple, and white Dust.

It appears that Dust behaves differently in the "White" Trailer than in the series, possibly due to it still being an early concept when the trailer was made. Therefore, some of the things Weiss is seen using it for in the "White" Trailer may no longer be possible in the series.
 * Fire - Red Dust; first seen "The Emerald Forest," when Weiss accidentally sends a line of flame toward a tree.
 * Ice - Dark blue Dust; Weiss uses ice Dust the most out of any other type, and is seen using it in a variety of ways:
 * Ice crystals - First seen in the "White" Trailer, Weiss has shown the capability to create a wall of ice crystals on the ground.
 * Sheet ice - First seen in "Painting the Town...," Weiss has shown the capability to form a thin sheet of ice on the ground.
 * With glyphs - Weiss seems to use her glyphs to manipulate what shape the ice will take. In "Painting the Town...," she places glyphs in front of Ruby's Crescent Rose to cause the bullets fired through the glyphs to erupt into ice crystals upon impact with the Atlesian Paladin-290. In "No Brakes," she uses a glyph to encase her team in ice, protecting them from a powerful impact. In "Breach," she uses a glyph to shape the ice into a giant sword.
 * Lightning - Yellow Dust
 * With glyphs - First seen in "Painting the Town...," when she fired a yellow streak from Myrtenaster onto the ground beneath Blake to create a haste glyph.

Trivia

 * According to early concept art of Weiss and her weapon, it seems that Myrtenaster did not have a conventional hilt, but instead possessed a classic gun shape, with the barrel lengthening into the blade and a magazine or grip behind where the Dust was supposedly loaded.
 * The penultimate concept had red Dust in all of its chambers to match Weiss' color scheme. Monty finalized the concept by changing the Dust to multiple colors when he decided it would be best to color code Dust.
 * Myrtenaster (Myrten Aster) is German for a family of flowers (Myrtle) that are typically found to be white, but can come in a variety of other colors.
 * Unusually, although Weiss is left-handed, she holsters Myrtenaster on her left-hand side. This stems from Myrtenaster's origins as a pistol as well as a sword.
 * Unlike many common rapiers, Myrtenaster does not have a knuckle guard or quillons, possibly due to the hilt configuration. It also does not have a particularly heavy pommel.
 * Myrtenaster can be seen simultaneously as the most static and dynamic of all the weapons in RWBY. Despite Weiss' rapier never changing its physical form, since she can change her semblance using the Dust loaded inside, it can adapt to any situation.
 * Whenever Weiss charges with her weapon, a high-pitched screech can be heard.
 * Weiss is still yet to be seen using her Semblance without her weapon.