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human
[MCU] does it hurt Thor to use lightning? Was Thor lying when he said “you lack the strength to wield it” about Stormbreaker?

He almost always yells when he uses lightning 

For Stormbreaker, he says that to the Guardians, yet Captain America easily holds Stormbreaker, but Gamora and Drax are around or even stronger than base Captain America.
gpt
He yells because it’s an impressive show of strength and power—like yelling “HI-YAAH!” in karate.

Keep in mind that Cap was already worthy of Mjolnir, so it’s not a stretch to assume the enhanced durability hadn’t worn off yet.