Yes but that’s not “random” its occurring because the value close to 0 is no longer being removed.
so you have a few verticis that are probably weighted on different bones.
dropping the weight when the value is near 0 (at .01) prevents the 2 interference or the 2 weights values.
not dropping said value causes a spike on those vertices that slightly exceed and therefore intersect.
Also,
You can’t expect someone else’s skinned mesh to work fine while pushing the limits.
To push the limits you actually need to create perfect assets with all the needed bits, pieces, and most importantly LOD levels.
Within the FBX you shared for instance, the whole elbow bend looks like a noodle. That’s definitely not anatomically accurate to the start with - unless you are actually mr fantastic or Gumby…
If you search you can find some perfect anatomical scans for both female and Male bodies that are actual scientific work, complete of underlying musculature, organs and bones. Ideally (though the last file I opened was close to 1gb) you could start off from the skin of one of those files and already get a better result. (Licensing wise would have to probably pay to use in the end product, but its usually provided free to study)
While we are on the subject of realism, how many bones do you have between the elbow and your shoulder?
What about lenghtwise between elbow and wrist?
Therein lies your second issue.
probably also why the elbow is bent like rubber.
To achieve realism you have to emulate an actual skeletal structure as much as possible.
That means 1 bone between articulations, and some times an optional parallel one for limiting or twisting (radiai and tibia, forearm and shin area)
Also, It’s actually simple enough to re-weight paint the whole armor loop by loop to have all values above .01 when you have to do the whole armor anyway.
What isn’t simple is spotting which of the vertices you are having problems with and what bones they are responding to when you utilize the automatic weights from blender as a basis…