"...Watch this."
With those short words, Aslaug took flight. She instantly enlarged the mythril spear she had shrunk to the size of a palm and transformed it into a bow. While the wolf on the ground was attracting attention, she fired a rapidfire volley of magical arrows at the troll’s entire body, from its torso to its head. A direct hit!
"Oh, by Thor's barbaric courage! An arrow of azure light out of nowhere!" the skáld exclaimed in awe.
Apparently, he wasn't much of a fighter.
"Like I said, magical energy."
Feeling a flicker of annoyance, Aslaug aimed a powerful magical arrow at the troll's heart. It pierced through! The monster stopped moving abruptly, a gaping hole in its chest. The wolf howled loudly as if congratulating her.
"Great job, Princess! Magical energy sure is amazing!"

Fate/Lost Einherjar, Chapter 2