I am about 3/4 of the way through Oathbringer so please do not include any spoilers in your answers.
I am a little confused about Shallan's lightweaving. The way I've understood it, is she basically uses stormlight to create images of other people/things. Generally, she is attaching images of Veil/Radiant/etc. to herself. That all makes sense. What doesn't make sense is how the personalities of each of those personas she's created seem to be attached to the lightweavings and I don't believe that's how they work.
In short, I don't understand how Shallan can't summon her shardblade because of her history with the thing but Radiant can with no issue. She's still the same person and unless the lightweaving changes her personality too, Radiant should have the exact same issue with summoning the shardblade as Shallan does. This issue arises for me in many other areas with Shallan's character. I love these books but with my current understanding of lightweaving, Shallan's character seems a little broken or unrealistic to me.
Any help/explanations are greatly appreciated. And again, please note that I am only 3/4 of the way through Oathbringer so please no spoilers.