What exactly does defense do?

solderboyjx25

i thought defense up increased armor by 50% and defense down in decreased armor by 50%

if this is the case, it is not exactly working and this could be for a number of reasons:

1. armor and resistance is still not strong enough ex. if 100 armor reduced 100 damage, then defense up will give you 150 armor which reduces... 150 damage... wow what an improvement

2. or the buffs may not be working properly at all

so what exactly does defense do because I am not seeing any changes?