Removal of Weapon Grades

While I understand what you're saying, the giant field bosses also follow this trend. Giant field boss weapons always have a fixed amount added onto their base, then the grade applied to it. For example, the Bastard Sword you're talking about is clearly a +5 variant (10+5+Grade bonus). The problem with listing the grades is that stats are always randomized with the field boss or external source exception (solea chest weapons with 25 dura for example).

This is where the problem comes in. Remove the grade info from the item grades list (since it is truly random within the set range with no weight at all) and you've just got the drop list. If a certain source has more dura than normal, then you should specify it on the drop list. For example, you could put Desert Dragon (15~19 dur) or something of that nature.