In Thor: Ragnarok, Hela destroys Mjolnir
We later know its forged in Nidavellir, an Alderson Disk built around a neutron star.
I don't have much to do thanks to User:Dino W's calc
To note, the entire beam is focused on the kiln used to melt Uru, unlike that Thor durability calc where we use only the area of Thor exposed. The same kiln is used to make both Mjolnir and Stormbreaker, it's kind of like a solar water heater.
So the cross section would change to 7.1631454094501 meters^2 .
This puts it at around 2.24932859e22 joules or 5.376 teratons.
Light and literally any radiation travel in a straight line. Since Thor was standing in the way, he would have blocked his portion of 0.856 teratons. This lowers the energy received by the kiln to 4.52 teratons. Remember that Uru didn't instantly start to melt so the minimum amount of energy the kiln required for Stormbreaker.
No here's a part. Stormbreaker is bigger than Mjolnir. Mjolnir in canon weighs 42.3 lbs (19.2 kg. You can easily put it on a table or hang it from a cloth hanger). Let's assume Stormbreaker is around 50 lbs (22.7 kg).
To melt 22.7 kg, it requires 4.52 teratons.
So to melt 19.2 kg, it would require 3.82 teratons.
So Mjolnir is about 4.5 times durable than Thor. Hela crushed the hammer when she weakened (her torn clothes and limping walk are evident at that point), and gradually got stronger as she spent her time on Asgard. You may say that Awakened Thor harmed Hela, but no, he didn't do much. When Thor unleashes his true potential, he emits lightning from his eyes and body and yet Hela easily deflected his attacks and even withstood a powerful lightning bolt that destroyed a portion of Rainbow Bridge.
When Thor held open Nidavellir's iris, he wasn't emitting lightning, which means he was weaker then. Thor in that form was easily overpowered by Hela, she was only harmed by Gungir's piercing damage.
So my proposed power rating is
Hela: At least Small Country level (Easily shattered Mjolnir when weakened, and gradually grew in power as she stayed on Asgard. Easily overpowered an Awakened Thor with Gungir and slashed his eye. After Thor unleashed his full power he was able to only stun her. Pierced through Skurge's thick Uru metal breastplate. Slammed Thor through Rainbow Bridge crystal shards. Was too powerful for Odin to kill her). Higher with bigger blades (Pierced Surtur with the Eternal Flame)
Awakened Thor: Large Island level+ (Should be comparable to his durability. Briefly held his own against Hela and slightly staggered her but was quickly overpowered). Small Country level at full power (Stronger than before. Managed to stun Hela. Can hold his own again Thanos. Broke a section of Rainbow Bridge with a lightning bolt. Instantly covered Wakanda in a thunderstorm). Higher with Mjolnir and Stormbreaker