Hi there!
I don't have those but there are some things you can do (assuming those particular engines because you mentioned them somewhere else):
- In Unity you can use "Grid by Cell Size" (https://docs.unity3d.com/Manual/SpriteEditor.html). That would require some manual adjustment for big enemies, weapons and knights.
- No much experience with GameMaker but seams like "Load a strip image" option might be what you need.
- If really needed you can extract elements yourself using something like https://imagesplitter.net/ (upload -> split image -> 16x16, png -> split image). You can automatically extract knights and most of the weapons by splitting 16x8, but you will still have to deal with bigger enemies manually (there are only 3 of them though).
Good luck :)