THIS IS THE REPONSE I GOT WHEN ASKING ABOUT +5 100% SUCESS RATE WITH TRINA :
Thank you for contacting Knight Online Customer Support with your inquiry. The Trina's piece and Tears of Karivdis are both used in weapon and armor upgrading. They increase the success chance of upgrading regularly weapons and armor, and rebirthed weapons and armor respectively. There is still a chance the weapon/armor piece can break, however. If these items are lost during the process of upgrading, they will not be replaced. This is an intended game play mechanic. There is no item available in the game that will guarantee a 100% success rate in armor upgrading.
Please feel free to submit another ticket if you have any other questions. Thank you for playing Knight Online and happy hunting.
Knight Online Customer Support