[Blasphemy/Trigger Skills] Weapon loadouts and skills within skills

So today after some extensive testing and hairpulling I found a "bug" or at least something that's very unclear.
At first it appeared after I had respecced all my split talents and focused my build down one path, thus making one of my old weapon loadouts obsolete (as planned). This Happened to be Weapon set 1 and thus since I no longer had any split points and no more skills for that set I moved over my weapon from 2 to 1. Didn't think all that much about it and logged out.
Then today when I logged back in I noticed that my Blasphemy aura with Despair put into it wasn't active when I was using my first weapon slot, it worked in the 2nd (where I had no weapon) and when I transformed into demon form.
My first instict was to check which loadouts Blasphemy was active in and it was indeed active for all 3 (weapon 1, 2 and transform) but still the aura did Not appear.
At this point I was starting to suspect a bug but decided to do some testing, I took off All spirit spenders and only had Blasphemy on and with Despair in it consumed 0 in weapon set 1.
I then swapped out Despair for Temporal Chains and Flammability which both worked without any problems.
Whilst writing up a whole rant to a friend online I mid rant thought that "Hey maybe I did something to Despair" so I popped despair out of Blasphemy and into it's own slot and Behold the culprit of it all:
Despair had it's active weapon sets set to 2 and Transform, since I used this skill in those loadouts Before I unlocked Blasphemy.
As soon as I swapped it back to being active in all slots and put it into Blasphemy everything worked as it should.
If this is intended then I Highly suggest against it since that's not only frustrating and unclear but also kinda shit design.

tl;dr: Skill gems put into other skill gems doesn't share the respective weapon set choices of the Parent gem.

Thank you for this, I was so confused as to why blasphemy wasn't working on weapon swap.