If a character has equipment that gives a bonus to D.T. and a larger bonus to D.T. against a specific damage type, the latter bonus will suppress the former, even though the former protects from more attacks.
Steps to reproduce:
1) Equip a character with any equipment that gives a bonus to Damage Threshold (e.g. Fine Breastplate)
2) Equip the same character with any equipment that gives a larger bonus against a specific damage type (e.g. the Nature's Embrace belt)
Expected behavior:
The specific D.T. bonus should only override the general one when the character takes damage of the specific type. In the current implementation, obtaining bonuses against certain elements can leave characters more vulnerable against all other damage types.
Attached:
Screenshots of the same same character's character sheet with and without the Nature's Embrace belt. Note how removing the belt increases the character's D.T.