He uses short swords because longswords get stuck in cave walls.
Goblin Slayer : The Gritty Reality of the Low-Level Grind In a world where legendary heroes hunt ancient dragons and demon lords, most adventurers overlook the small stuff. But in the dark fantasy series Goblin Slayer , the "small stuff" is a lethal plague. Since its debut as a light novel series by Kumo Kagyu, the franchise has sparked intense debate for its brutal depiction of a world where one mistake in a "starter" quest can be a death sentence. A Hero Defined by Trauma Goblin Slayer
He wears cheap, light armor for flexibility and a helmet to prevent head trauma. He uses short swords because longswords get stuck