Changing the colour of a Niagara effect in a slash animation

Hi I’m hoping for some help as I am pretty new to UE5.

I have made a material for a sword trail VFX (when a sword slashes it leaves a trail behind). I have the main material → material instance with a changeable colour parameter. The material is then used in a Niagara VFX system.

There is a character animation linked to the model and on the bone, I have added a socket where the VFX trail sits, it is then in the timeline and plays when the animation plays.

This works but now I want to change the colour (“Emissive colour” in the instance material) of the trail based on the speed of the slash (the animation is a spinning person and there is already a variable recording the speed of the spin).

The problem is, the VFX is not a BP class, and I don’t know how to access or add it to the blueprint of the animation or how to add the colour change. Any help would be appreciated.