Marvel's Eternals introduced Dane Whitman (Kit Harington) to The MCU, and while Sersi's love interest only had about 10 minutes of screen-time in total, the post-credits scene teased big things to come for the character.
The stinger saw Whitman reach for the Ebony Blade, setting up his eventual transformation into the Black Knight. Before he could lay his hand on the sword, however, an off-screen voice warned him about the dangers of wilding the blade. We'd later find out that this was actually the MCU debut of Mahershala Ali's Blade.
There's been a lot of speculation relating to what this scene was setting up. We know Ali will lead the upcoming Blade reboot, but will we see the Daywalker team with the Black Knight? A recent casting breakdown indicated that Dr. Faiza Hussain may also be joining the fray, which could open the door to MI13, Excalibur, and the further exploration of the fantasy/horror corner of the Marvel Cinematic Universe.
We're going to have to wait and see what Kevin Feige and co. have in store, but director Chloé Zhao did confirm that the stinger "sets up so much" while speaking with production visual effects supervisors Stephane Ceretti and Mårten Larsson for the film's Blu-ray audio commentary.
Here's the exchange (via MCU Direct).
Chloé Zhao: "Ebony Blade, who would have thought. I definitely geek out quite a bit, especially when the voice that comes in the end."
Mårten Larsson: "It's just a cool post-credits scene. Simple, but sets up so much."
Chloé Zhao: "Sets up so much... And, I love this effect they use on the sword so much. Did we use... Was it sand magnets?"
Stephane Ceretti: "It was magnetic ferrite... I think it's cool."
Chloé Zhao: "Yeah, the idea of a blood curse, how to show that."
Zhao doesn't give much away here, but it sounds like she has some idea of what's to come for these characters, which could mean she's going to be involved in some way moving forward.