It does make sense that Psylocke is capable of killing Magneto. Despite having the fight in a forest without too many metal, Psylocke is still uniquely equipped with the tools to take down the Master of Magnetism. She can use a psychic blade instead of relying on metal. She’s a ninja so she’s quick and she can get near Magneto. And if he ever makes the mistake of dropping his helmet in midfight, he’ll be vulnerable to her telepathic attacks.
Elixir would later pop in with Exodus to heal Magneto.
From – Uncanny X-Men Vol. 4 #19