I figure the never ending list of oddities with the "magic" shield is due to the original code being totally incompatible with the concept.
The programmers must of been under some pressure to hack the original code to "make it work". There's no consistency in how the shield is managed relative to all the other weapons and equipment which is an indication that the thing was "forced" into the existing code.
In the physical world, it is common knowledge that when your infrastructure does not support what you are adding on to it, it tends to rattle, sway, buckle, make lots of noises, and eventually collapse.
It's a damn good thing programmers do not build bridges
