Balancing DLC equipment is tricky. Considering that you basically get extra Feat points with money (since you unlock all DLC content without any additional Feat points) you’d run the risk of obsoleting existing Feats if you could just shell in some dollars and buy the feats for all tiers of equipment. So in fact DLC weapons would need to be a little weaker than their vanilla counterparts or you could purchase an advantage in-game with money.
The pre-order armors and weapon are in a similar position - you don’t want to give an unfair advantage to people who bought the game in Early Access. A nice, mostly cosmetic reward is okay, but not something you can make from the get-go and wear throughout the game.
The DLC weapons aren’t underpowered, they have normal stats for their tier and can easily be crafted as exquisite or flawless versions since any T4 blacksmith can craft them.
If anything, the level 60 version of Conan’s sword could use a slight buff or it should be changed to not require starmetal since it’s worse than a normal starmetal greatsword or even the acheronian greatsword.
That’s what makes this tricky, though. Because if the weapons are weaker, there’s very little point to them - free feat points or not. Same goes for both the pre-order items. On the other hand, while free feat points is not a massive advantage, it IS one all the same - and everyone hates Pay2Win, no matter how little advantage it grants.
The right thing to do would be to tie their availability to the their vanilla counterpart, the same way building pieces are.