So if Dave Filoni and Jon Favreau decide that Phasma's baton was actually Mando's Beskar spear that's good enough for us. (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.)

What is Phasma spear made of?

The baton's durable cylinder was made from a collapsible micromesh matrix held in a containment field. The baton had different forms depending on its state: when the baton was inactive, it condensed down to a small baton; but when it was active, it instantly expanded to its full length.

Who did the Beskar Spear belong to?

Affiliation. A spear was wielded by the Magistrate Morgan Elsbeth on Corvus during the New Republic Era. The staff was made of pure beskar, a metal alloy tied with Mandalorian culture. After Elsbeth was defeated by the Force-sensitive Ahsoka Tano, the staff was given to the Mandalorian Din Djarin.