Hmm, yeah that scene struck me as odd when levelling an alt since, as you said, "a good portion of that scene was fiction on her part anyway" but you're right, it does imply she was also sundered.

I still haven't found anywhere saying she gathered her shards early on, or anything that explains why she got weaker with each rejoining. It's clearly stated many times that she does get weaker, but the 'why' of it always confused me.

Really, with EWs many plot-holes this one is fairly minor, but it does seem like that bit of lore should have led somewhere since it was restated in EW. If not leading somewhere in the current story, leaving that concept in a fuzzily worded, long-past quest would make more sense... unless a hasty rewrite was done and that line was accidentally left in, which is looking more probable now.