With mines and bombs the shield stats will show the real differences, as their effect is a know constant, but things like rockets, missiles and plasma bolts also depend on the proximity of the craft firing the weapon.
The only way to test that is offline two play mode with one craft ahead with shield ready to activate, and another behind at a set distance.
Once both craft have the needed pickup's, place them on the track for the test, arm the forward ones shield, then blast it with the craft behind, note the shield loss of the craft ahead to give you your stats.
Do the same test again with the same craft weapon combo, but this time further apart.