Crocea Mors

Crocea Mors is Jaune Arc's weapon of choice. Jaune states that it was passed down from his great-great-grandfather, who used it in a war.

Description
The sword itself is a simple longsword with a blue handle and a golden cross-guard. Jaune can transform the sheath into a shield for combat. The shield is a silver Heater Shield with a gold trim, and it shows Jaune's symbol colored in gold in the center. His explanation for the transformation is that when his arm gets tired of carrying it, he can shrink it down, to which Ruby replies, "Doesn't it weigh the same?", which Jaune sheepishly admits is true. Despite it being an antique, it seems to be very well-made and durable, being able to block a blow from a Death Stalker and Cardin Winchester's mace with no apparent damage.

The "Shield" appears to deploy with enough force to get its tips embedded into the doorway in Jaunedice.

As of Forever Fall, Pt.2, both the sword and sheath are shown to be incredibly durable. The sword is sharp enough to decapitate a fully armored Ursa, while the shield is strong enough to take several direct blows from the same Ursa without any visible damage.

Trivia

 * Crocea Mors is Latin for 'yellow death' and the name of Julius Caesar's sword in some legends. Appropriately, the same legends have it becoming embedded in a shield.
 * Before its name was revealed, Crocea Mors was called Sword and Shielth. Jaune's voice actor and writer of RWBY, Miles Luna, acknowledged the name created by the fans and decided to use it during the interviews before Monty Oum decided to reveal the true name of his creation via Facebook.