Just like any other class, Death Knights have three different trinkets at their disposal in the beginning. Unfortunately you can only use two, which makes narrowing down your choices a little more difficult. Granted, they will come with completed quests, but once you have more than two the usage will be based on how you equip your Death Knight. Here is the three you start out with during your Lich King quests. Reading over their abilities outside of the World of Warcraft game may help.
Soul Harvester’s Charm
Listen, we’ve created six different Death Knights and each one is equipped with the Soul Harvester’s Charm trinket. First off, it improves your critical strike rating by 20. Since your Death Knight will be geared towards gaining DPS stats, this is essential during your gaming. While the critical strike is nice, you will also gain a huge parry increase (90) for ten seconds. Keep in mind this only happens once an enemies melee attack knocks your health down to under thirty-five percent.