Item description:

Historian & Firestarter

1. Once loaded go ahead to start the fight.
2. Guard Harofsen will spawn last Winter Shard for you to destroy. (Firestarter)
3. After you defeat Guard Harofsen and his minions there will be a cutscene. At the end of it you will get the "Historian" trophy.

If "Firestarter" trophy doesn't pop up then you need to redo this mission.
The "Synergized Trophy (Good Spot)" from EXTRAS folder is save state before starting this mission.
You have to load it, select main quest and continue till you reach point showed in this video guide by PhatSteve7: [ Register or Signin to view external links. ]
Then just sipmly follow his guide and you should get this trophy.