Question: Does Guts have two different swords, or is this just a difference in the way it was drawn?
guts uses the smaller sword during the golden age arc, which is basically the first 12-13 volumes. at the end of the golden age arc, griffith rapes casca until she becomes retarded, right in front of guts, while demons rip guts' arm off and poke his eye out. he loses consciousness and wakes up a week later at this blacksmith's house. the dragonslayer (big sword) was already at the blacksmith's, and guts asked if he could have it. blacksmith says sure why not.
He used a total of three swords,
Thousand limbs (the sword used at golden age)