all shields are based on a unit's base resistance. the base resistance is the number you see when you open your character interface. it never uses buffed resistance.

gakido may have had his resistance buffed by 60% within the battle, but since shields don't take into account the buff, you don't get 60% more shield regardless of how much gakido's resistance is buffed.

not everything that goes wrong is a ripoff...sometime you're just misinformed.

icex has been over this several times in his guides, i believe. it's all public information. mayhaps you would like to check it out?