Unofficial Fallout 4 Patch

Following the lists down from 00248487 leads to the following armor in both cases. There is no indication that this armor goes to a T60 or is referred to as Hydraulic Bracers.

Attached Files:

RaiderPA.png

I am sorry, I don't have the CK installed any more. What you show looks to me like the base armor record. Hydraulic Bracers are a PA arm mod, that increases unarmed damage, see here:
https://fallout.fandom.com/wiki/Hydraulic_bracers_(Fallout_4)

Tessa's Fist is equipped with such a mod. Based on my limited understanding, equipping this mod is handled at runtime by the CustomItemQuest [QUST:0022576B].
Here I can see an entry for Tessa's Fist in XEdit, that links to the Form List CustomItemMods_DN109_TessasFist [FLST:00248488].
In it I find referenced PA_T60_Arm_Misc_Unarmed "Hydraulic Bracers" [OMOD:00203748].
My guess is that this needs to be changed to PA_Raider_Arm_Misc_Unarmed "Hydraulic Bracers" [OMOD:0020374A].

Unique items such as Tessa's Fist are not only equipped at run time, but also created at run time, by adding a selection of mods taken from a form list to an appropriate base item via script commands. When mods are added by a script command, the usual restrictions (i.e. matching mod association keywords) do no longer apply (papyrus does not check them, only the workbench code does). Thus, unique items can be unique in two ways: by using unique mods that cannot be constructed by the player or by using unique combinations a workbench wouldn't allow. Therefore, the use of the T60 mod instead of the corresponding raider PA mod may be deliberate (assuming that it has the better stats).

And BTW, you cannot modify unique items at a workbench in the vanilla version of the game.

All Hydraulic Bracer mods have the same Enchantment: EnchPA_UnarmedDamage "Hydraulic Bracers" [ENCH:001D6CCA], so their damage enhancement is identical.

Of course you can mod unique items in the vanilla game. You can't mod their legendary attachment, but that has nothing to do with this bug report.