I'm not sure, but it seems to me that Guts' armour changed a little somewhere between vol.17 and 20 (i think, but 15-22 is right in any case). Namely, in older volumes, (for example, when he was fighting those fake elves) he had only leather between his knees and groin, and in vol.22 (example: when he comes back to Godo's place with Casca), he has IRON greaves (or whatever they're called) up to his groin? Did his armour change at some point, without me noticing, or is it only my imagination?