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@naman Looks like the subdivision artifacts are caused by a combination of issues. The curvature at the bottom of the guard is deformed by the intersecting shape and the extraneous loops that run across the intersection are pinching in the corners.

Similar to the previous examples: both of these issues can be resolved by using the existing geometry in the curve as support and terminating the extraneous support loops with a triangular quad, n-gon or triangles.

Another option would be to increase the number of segments in the curved section. Which would provide a path for each of the support loops on the intersecting shape but would also make the base mesh too dense to edit efficiently. These results aren't much better than the previous topology strategy. So, all of the added geometry doesn't really make sense on something so small.

Most smoothing artifacts on curved surfaces can be resolved with the same basic subdivision modeling strategies: line up the segments in the adjacent shapes, use the existing geometry of the curve as support loops for the base of the shape intersection, and either join the support loops from the shape intersection into existing segments on the curve or terminate unneeded support loops between the edges at the base of the shape intersection.

it's dotproduct of a view/camera and a pixel normal vectors ( Fresnel gradient) remapped to some special cube map texture or a gradient . pretty sure should be doable in SPainter too but i never tried. In Blender viewport it's simple like this .