Finding speed modifiers is not as easy since they do not change.
My advice is to find something related to your character or weapon, and in that area of RAM simply start changing things until you find something that changes the speed of your attack.
Use the real-time hex editor to easily see a lot of the data related to your player and attack.
Find your player HP as you have done, then view that area with the hex editor.
Attack and you will see values changing to blue. These values are related to your attack. But your attack speed won’t turn blue since it will not change. You have to look for it in that area.
Prince