Is there some kind of trick to beat Barachiel?

The best way that I've found to beat him is to be level 19 or higher (for all characters) and to use Reimei's Torch Bow. Run from him as much as you can and use blindsides frequently. When he uses Dragon Tornado and is on the ground, use a special ability (I used Reimei's first ability, not the newer lightning/thunder one). You deal much more damage when he's on the ground and often get the same results when blindsiding. AS far as setting tactics, I had everyone in fight freestyle besides Lymle, who I had in 'stay out of trouble'. If you have a few fresh sage on you and plenty of bigberries, blueberries, and other assorted berries, you should be okay. It took me a two tries, but in the end this worked well for me. Good luck.

Also do NOT use Water/Ice element attacks/symbols (that means you Faize!). Water/Ice elemental attacks will HEAL Barachiel rather than hurt him.

I was around lv 18-20 when I fought him, I used this strategy.

Remember to stack up on healing items before the fight. Barachiel's weak point can only be hit when goes down to use his attack.He is also weak to fire, so controlling Lymle isn't a bad idea.

Firstly, use edge to run around and wait till Barachiel uses the attack that brings him to the floor. Then switch to Reimi/Lymle and attack him with your best ranged attacks (sonic thorn/hatchet reel). Just continue to use this strategy till he gets defeated. Hope this helps. =)

You need two hit him when he comes to the ground and then give your best rush combo also if you are using faize turn of his ice needles if he has that skill

I think he's weak to fire. And whenever he plunges into the ground his weak spot is exposed, so attack with your most powerful character/attacks then.

What worked for me. I think i was level 18 back then.
1 .Set Lymle to "stay out of trouble, the "hide" skill and use hatchel reel when he lands and glows (Most Important!)

2. Control Edge and use taunt on the Barachiel. Run around and blindside whenever you can.

3. If you feel you are underlevelled, set your BEAT to neutral

4. For Reimi, if she learnt focus just keep using that

5. Bring plenty of fresh sages and blueberries

6. You will know you are close when he uses his ice special art instead of his usual one

After around 10 mins he should be down

Also, spending the time and leveling up the fire bolt skill really helps on this guy. Just let yourself get ambushed a couple times to get the SP Bonus tiles and you'll have that skill maxed in no time.

Use fire based attacks and when he slams on the ground attack. His back is his weak point and that's really the only way you can hit his back.

i put the whole party on "do nothing", put them aside, and killed it solo with reimi. costs you way less of your valuable nerves. just blindsiding it, and then rush+ sonic thorn, whenever it decides to get stuck in the ground for a longer period of time (the green glow signals it will be a short time). i got sick of the party members breaking his "being stuck" before i could do some REAL damage. i got sick of healing and reviving them all the time. this way, all it took was a handfull of blue and blackberries. and it went down with ease :3