M. Night Shyamalan's Unbreakable is one of the writer director's most popular movies. While talk of a sequel had been around since the original film's success, it was when 2016's Split, that turned out to be set in the same universe, met with equal success that we finally got the return of Bruce Willis' David Dunn and Samuel L. Jackson's Mr. Glass. Glass was, for many, not quite the ending to the story that fans were hoping for, but the director defends the end of Bruce Willis' character in the film, saying that it makes sense based on the point he was trying to make.
It's established in Unbreakable that David Dunn's weakness is water, but I'm not sure anybody was quite prepared for seeing the character ultimately defeated in Glass by being drowned in a simple puddle of water. It certainly wasn't a heroic or noble end for the superhero character. However, as M. Night Shyamalan recently explained to Uproxx, that was exactly the point. As the director says...
Well, in the end, that the simplest thing can take the strongest person down. That it’s like more of Achilles’ heel that, in the mythos of it, you don’t need an army to take down the strongest man if you know their weakness.
The move certainly succeeds in showing David Dunn's weakness. It reinforces the "reality" of the whole superhero situation in the movie, that these powers and the associated weaknesses are real, due to the fact that something as simple as a puddle of water can overcome the man. It's a bit anticlimactic and potentially unsatisfying for the audience, but sometimes the unsatisfying resolution is exactly what the filmmaker wants.
And it has to be said that, for better or worse, there's no indication that M. Night Shyamalan has ever done anything with his stories than exactly what he wanted. Many of his movies have been praised and just as many have been seen to have significant problems, but they're all exactly the movie he wanted to make. He doesn't tell the story that he thinks the audience wants to hear. He's always making the movie he thinks should be made. Sometimes it works. Sometimes it does not. There's been some sort of twist in nearly every movie the man has made and sometimes they work and sometimes they don't but they always mean something that the director feels is worth saying.
While it seems likely that the world of Unbreakable and Glass have reached a conclusion, whatever M. Night Shyamalan does next on the big screen, if he ever goes back to it following his Apple TV+ series Servant, you can be sure it will be the sort of movie that has people talking. The only question is whether what people will be saying is good or not.