Throwing knives were a weapon of choice for Judeau, and later Guts.
These knives are first seen used by Guts, and chronologically by Judeau. They are fairly small and fin-shaped, triangular with curved edges leading to a point, somewhat resembling an arrowhead. The handles are small and thin and align with a ridge down the center. Judeau at first held them in straps on his legs, then in a strap across his chest, which Guts mimicked.
These knives depended on accuracy, and being too small to do massive amounts of damage, often needed to be thrown at vital points to achieve lethal effect. Guts primarily used them when stealth was necessary, opting for the repeater crossbow in situations where less accuracy and attention to ammunition was required.
These knives were Judeau's preferred weapon, and were later used by Guts in his memory. Judeau used them to kill two guards during the mission to rescue Griffith, landing them both in the men's throats. Guts is first seen using them to take out two soldiers guarding the Count's quarters, who fell dead before being able to utter anything. They were also used against the Count himself, though they were to minimal effect due to the Count's incredibly soft body. They failed again when aimed at Rosine, who deflected them with her proboscis.
As time went on and Guts gained other weapons and strategies, he began to use them less, as the miniature bombs he uses provide more reliable impact and the repeater crossbow being more forgiving towards ammo consumption. Guts appears to retrieve the knives after the chaos of his battles ends as they are usually seen with him afterwards. However, after the Berserker Armor is acquired, they virtually disappear from use.