I wish more Hollow Knight fan created content focused on the fact that it's very likely any void being can achieve a state similar if not identical to void heart.
"An emptiness that was hidden within, now unconstrained. Unifies the void under the bearer's will."
In my eyes this dialogue doesn't have to only apply to the knight or vessels as a whole... They're under similar circumstances to a lot of other void constructs, just that ghost survived long enough and got to challenge their purpose which then "unconstrained" their true nature.
I like to think Lost Lace also achieved a partial version of this... Obviously not the real united void stuff, she's made out of pure soul after all, but; Unlike any void construct (Excluding Ghost!) she has genuine control over the liquid void that seeps into the cocoon over the fight... a good chunk of her attacks ARE just manipulating said void! It tracks with the theme Hollow Knight established with Ghost defying their creators' will and working by their own to stop Radiance, similarly to how the entirety of Act 3: ABYSS is caused, and is centered around Lace's 'victory' over Grand Mother Silk in defying and denying her the ability to bind Hornet and get revenge on her daughters.
Another thing worth noting is that not all of Lace's new abilities are combat focused! In Hollow Knight you can find a royal retainer in the Abyss' lighthouse with the Dream Nail dialogue:
"...Turn it off?...Cannot..." "My King. I'm sorry...the sea calls..."
Back then, it was sort of unclear how the void could convince someone to do really anything, let alone defy an order from a pale Wyrm, but now we know!
In Silksong's abyss, right before the getting the ASCEND: Return to Pharloom wish and right before the Last Dive, Lace shows herself despite being trapped deep within the abyss inside of GMS' cocoon. I immediately interpreted this as an explanation as to how the abyss could reason with people while being an unorganized mess, it could always make projections! Just that lace exploited that ability to talk to hornet in this instance :)











