Handheld light customizability is currently very limited.

ideally, a slider with ranging intensities should be implemented instead of the 2 avaliable (Subtle, Normal)

And. The ability to reduce the range of the handheld light (currently the range of the light is ridiculously large) similarly to optifine/lamb dynamic lights range (Basically regular lightning and vanilla range when light blocks are placed down)

"Why not just use lambs dynamic lights?" Colored lighting is broken with that mod. Shader handheld lights are superior.

new intensity options will come in r5.6 afaik range option can perhaps be considered