The Last Remnant

This happens automatically during the story base battles on disc 2 but it's quicker to do the side-quest "The Silver Falcons Part I" which also unlocks this cheevo.

You need to recruit Caedmon and then talk to him a few times outside the guild in Baltrossa.

The Bloodhunter- Defeat over 30 monsters in one battle.

This is unlockable during the storyline. Shortly after starting the second disc you'll be tasked with assulting Koenigsdorf Fortress. You'll have to destroy 6 bases to get there. If you pick Base 1, you'll start the battle assaulting the base from the outside. There will be two batches of reinforcements from the enemies, and just make sure you kill them all (there's more than enemies between all the unions) before you kill the Tactics leader, and you'll get the unlock.

I've achieved this one during the last part of the secondary quest "Wisdom's Echo", there is a lot of enemies and you can let them follow you until you reach 8-9 followers (becoming 30 or more in battle). Before try this i suggest to make a little save so if you ingage the boss or make some mistakes you can retry.

I hope this help someone.