I have to say this. What you said about the guardian vs strength talismans is not absolutely true. I did all the math to calculate how the bonus stats works and realized that the set bonus apply on the base stat of the character. The bonus set doesnt include any stat provided by any talisman, so the guardian set (20% of DEF) apply on the character's base DEF and the strength set (15% of ATK) apply on the character's base ATK. Therefore you cant say guardian is always better than strength cause it depends on your character due to every character has different stats. Guardian talisman is better when your character has a lot of base DEF and strength talisman is better when your character has a lot base ATK. Base stats are the white numbers by the way.
Same applies on the Paladin vs Holy talismans.