The following contains spoilers for RWBY: Ice Queendom Episode 11, "Light in the Shadows," now streaming on Crunchyroll.
RWBY: Ice Queendom is a largely self-contained story that fits between Vols. 1 and 2 of the original RWBY series. While the story is designed to flesh out Weiss Schnee's transition from a narcissistic bigot to a loving, sympathetic individual, the anime still drops Easter eggs of events and developments that occur much later in the main series. One of the earlier hints from previous episodes that foreshadows Weiss's positive character growth is her dress from Vols. 4-7, which ends up playing a vital role in Ice Queendom.
Now that the anime is on its penultimate episode, another Easter egg is dropped that foreshadows a future character-defining battle, this time between Yang Xiao Long, Blake Belladonna and the latter's former lover, Adam Taurus, in Vol. 6. As originally depicted in the main RWBY series and in Episode 1 of Ice Queendom, Blake originally left Adam and the White Fang once their goals no longer aligned with hers. She then enrolled at the Beacon Academy to carve a new path for herself as a Huntress, and it was at Beacon where she met and befriended Yang.
Blake and Yang developed a close friendship during their time at Beacon that bordered on romantic attraction. While both girls did not initially act on those feelings except on a superficial level, when Cinder Fall, Roman Torchwick and the White Fang attacked Beacon, Blake was reunited with Adam and was forced to deal with the consequences of her past. When Yang attempted to intervene, Adam severed her right arm as a way of punishing Blake for betraying him.
Adam's violent attack left Yang with PTSD and struggling with depression during her recovery period. She also started using a bionic arm to replace the one she lost. Blake, however, was left with intense feelings of guilt and self-loathing. Rather than stay at her partner's side while she recovered, Blake returned home to her family in Menagerie, accompanied by her friend Sun Wukong. Though Blake reasoned staying out of Yang's life was the best way to keep her safe from Adam, Yang felt differently about her departure and took it as abandonment. This left her feeling hurt and angry at her partner in the year they spent apart.
When both women reunited in Mistral to prevent the destruction of Haven Academy, Yang continued to maintain some distance from Blake, having not recovered emotionally from her initial abandonment. It's not until both women end up in Argus as a pit stop to Atlas -- Weiss's home kingdom -- that they fully reconcile. While attempting to disable an Atlas communication tower in the city, Adam once again attacked Blake -- this time with the intent to kill her.
The moment Yang noticed her partner was in trouble, she once again came to her aid, only this time she didn't repeat her initial mistake with Adam at Beacon. Instead of impulsively attacking Blake's ex-lover like before, she engaged him in a more controlled fist fight, and waited for him to lose his cool in order to incapacitate him. Once Adam was parted from his weapon, Blake and Yang simultaneously impaled him with both halves of the former's sword. After Adam fell to his death, both women shared a tender embrace, with Blake promising Yang she'd never leave her again. All of this development is foreshadowed in the penultimate episode of Ice Queendom.
In the climax of Ice Queendom Episode 11, Yang's sister, Ruby Rose, succeeds in killing the Nightmare Grimm possessing Weiss. This allows Yang to fulfill her promise of saving Blake from the Nightmare Grimm possessing her. Despite her teammates helping in her fight against Negative Blake, the latter is not easily subdued. This is not helped by the fact Yang and her teammates are only fighting at half strength, not wanting to hurt their friend who's lurking underneath the nightmare. It's not until Yang manages to break Adam's mask that Blake is able to "wake up." From there, the fight sequence plays out almost identically to the fight with Adam in RWBY Vol. 6.
After confronting the version of Adam that exists inside her mind, Blake mentally liberates herself from the Nightmare Grimm's influence. She's also able to physically separate herself from her nightmare body with Yang's help, leading to a subtle replication of their tender embrace in Vol. 6. Unfortunately for both women, they aren't out of danger yet. Since the Nightmare Grimm is still possessing Blake's body in the real world, they still have to fight Negative Blake, resulting in a replication of the Adam fight. It even ends with Blake killing her nightmare counterpart by impaling her with her sword, just like she did to Adam.
Though Yang doesn't get a stab at Negative Blake, she still hints at her future killing of Adam when she tells her partner she didn't need to deal the final blow. She also coincidentally points out it's not good for Blake to fight against herself, further foreshadowing the latter's self-loathing after the fall of Beacon. While Ice Queendom doesn't go above and beyond what's already been depicted in the main RWBY series, the fact that it still replicated an iconic fight from a future volume solidifies Blake and Yang's romantic future.