If you equip multiples of the same Talisman you can make a set which will grant further bonuses.
Tapping on a talisman will show you the Set Bonus.
The talisman name generally indicates what the set is designed to improve:
|Strength||Attack +15%||Warrior characters|
|Holy||Magic +15%||Magus characters|
|Health||Hit Points +15%||survivability of any character|