Palace weapons are different.

First you need 30 arms/armour each to get an i235 weapon.

When you need an additional 60 of each to upgrade that from i235 to i255, so you need 90 in both stats for one Kinna weapon.

Palace can be great though to help you get armour, though you WOULD have to lore grind to get a full set of i230 armour/accessories before you can actually go into a dungeon, or you can buy up to i255 crafted gear on the marketboard, as well as crafted i250 weapons (They will be expensive though). But if you go the dungeon route, you can get up to i245 gear from the stuff that's in the Expert roulette.

As for Drk's 'artifact armour', I think it's just some of the exclusive stuff from an earlier tomestone set, since Drk/Ast/Mch didn't have anything at level 50 for their unique look, like other jobs did back in 2.X.