Pure Beskar is what keeps Din Djarin and so many other Mandalorians out of harm's way, but it wasn't always that way for the people of Mandalore. During much of the Clone Wars, many Mandalorians did not possess pure Beskar suits of armor, leaving them more vulnerable to blasters and lightsabers.
Mandalorian armor was traditionally made out of almost indestructible Mandalorian iron (beskar), but this was rare and expensive, so many Mandalorians, such as Jango and Boba Fett, opted for less durable materials instead, such as durasteel or duraplast.
The helmet, which was created using an alloy of durasteel, plasteel, and obsidian, had a sloped design for its sides and back similar to that of the helmets on ancient Sith armor. The helmet created Vader's menacing growl due to his natural voice being very weak from vocal-cord damage.
Death Watch had their own version of Mandalorian armor made from beskar that originated from the mines of Concordia. Their rank insignia was located on the left shoulder armor plate.
Boba Fett's armor was previously stated to be made of durasteel. However, "Chapter 14: The Tragedy" of The Mandalorian retconned the Fett armor into being made of beskar.
(Fun fact: According to Star Wars canon, Phasma's armor isn't beskar either. It was actually made using scrap metal taken from Emperor Palpatine's old yacht.)
Obsidian in the armor supercharged Vader's dark side power, turning anger into a power source. The Empire couldn't use beskar in the armor due to a lack of knowledge on forging the Mandalorian alloy.
While there is no in-universe canon explanation to justify that change in the Jedi's clothing, the Star Wars Expanded Universe established that wearing bulky armor could slowly interrupt the Jedi's connection with the Force.
All of Gideon's Stormtroopers were wearing beskar armor, and Moff Gideon's Dark Trooper armor was also made of beskar. The fact that Gideon's armor was beskar was an insult in and of itself.
One lightsaber strike cannot cut through the Mandalorian Beskar armor or a Beskar weapon. But if a lightsaber stays in touch with it for a longer period, it will melt it. It also depends on the wielder of the weapons. Jedis wield a lightsaber that is much stronger than a Mandalorian warrior.
The famed Mandalorian bounty hunter and foundling Jango Fett wore customized armor made of beskar alloy, which was later inherited by his cloned son Boba. The Arc Pulse Generator, an Imperial superweapon, was capable of superheating the beskar alloy used in Mandalorian armor to incinerate its wearer.
The starfighters were produced during the war between the Galactic Alliance and the Confederation. The starship employed Verpine ultramesh technology to produce a lightweight frame made exclusively from beskar, which made the fighter durable and maneuverable in the atmosphere.
Gwendoline Christie portrays Captain Phasma. The character's creation was inspired by a rejected design for Kylo Ren. Costume designer Michael Kaplan came up with the concept of Kylo being "the Lord of the Stormtroopers, in bright shining silver armor".
In contrast, Din Djarin's armor was made from pure beskar, earned through the bounty on Grogu. This made Djarin's armor rare and even more durable than normal Mandalorian armor, allowing it to stay shiny and undamaged even when he walked into a barrage of blaster fire.
Cherished for its incredible strength and durability, beskar was notable for being able to withstand blows from even a lightsaber, and was commonly thought to be nearly indestructible, making beskar more prized than durasteel or cortosis.
The black lightsaber, or Darksaber to give it its proper name, is one of the rarest lightsabers in Star Wars canon. Despite its rarity in canon, anyone who has seen the second season of The Mandalorian is likely to be familiar with the Darksaber.
At the time of The Mandalorian story, it is pretty clear that Moff Gideon is not a Sith Lord even though he has the Darksaber in his possession nor does he have any links to the Jedi. Moff Gideon is nothing more than one of the Empire's existing bad guys who officially worked for the Imperial Security Bureau.
The very first owner of the Darksaber was the man who created it, Tarre Vizsla. Very little is canonically known about Tarre Vizsla, other than the fact he lived during the Old Republic era and was, at that time, the only Mandalorian to have ever been accepted as a Jedi.
