There's a couple approaches you could take for this, and a lot of optimisations possible for each part, so take this more as a general 'approach' than a specific step-by-step
90% of the shield visuals are just driven by basic ol' fresnel plugged into the opacity output! Change up the colours, pattern texture, make it wobble however you want and away you go. You could get away with alpha clip transparency for a cheaper version
Hit VFX is comprised of some super basic burst emitter particles. Flipbook lightning, directional flares etc. - but there's some fancy stuff for the radial pulse/hexagons in the next vid! Most of these can use alpha clip too to cut down on overdraw
To avoid needing to pass excessive data every frame to the shields for hit positions, I just used a very shallow inverse depth test on a scaled sphere particle
And there you have it! Very customisable, the approach can work across any model with minor (and a potentially automated) mesh setup, and the only logic needed is to spawn a particle at the hit position
Now that Halo is being made in Unreal Engine, it seemed fun to reimagine what Spartan energy shields could look like with a fresh coat of paint — here's my take on some flashy shaders+vfx in engine! ⚡
Massive shoutout and credit to the McCarthy Bros for the great base model (I did have some fun making the custom visor material tho 😉) and making it available for download on Sketchfab. Here are their links!
https://artstation.com/shadowdragon811
https://sketchfab.com/joshuawatt811