Cuphead

You first have to do the Achievement "A Horrible Night To Have a Curse"

After you have done that you will get a charm called Cursed Relic.
The Cursed Relic gives you 1 HP in battle and it randomly assigns you with a weapon every time you press the fire button. But if you hold the fire button down and just keep attacking you will hold that weapon till you release or do something else like dodge

With this equipped you will have to defeat every boss in the dlc, then the relic turns in to the Divine Relic and you will get the achievement.
It has to be done on regular or expert difficulty(I tried it on simple and it did not work)

A few people have commented that you can do bosses from the main game aswell and the relic will turn in to the Divine Relic. You can also track the progress on the relic icon, after each fight the icons eye should open up more

A Tip to get trough this is spawning the genie before going in to a boss by spinning your left stick around, to get 1 extra HP in the boss room. You can also get 1 or 2 extra HP in the fight by doing a parry.

"Obtain great power" means that you have to fix the Broken relic into the Divine relic. Here are all the steps you need to complete.

• Buy and equip the Broken relic for 1 coin in the shop
• Solve the Graveyard puzzle to unlock the secret boss
• Beat the secret boss so that the Broken relic becomes the Cursed relic
• Beat 6-8 bosses atleast on regular difficulty with equip Cursed relic

Now a little detailed information about the individual steps

Graveyard puzzle

The solution to the puzzle is in the three statements of the three people on the winner's podium. There hide the directions in the messages. The order is first place, second and then third place. Unfortunately, these hints are different for everyone! In the spoiler you find many solutions which I gather together.

With your personal solution, now go to the graveyard and open the path to the secret boss.

Secret Boss

I personally stood all the time in the lower left corner and shot with the new red shot, the angel boss who then forwarded the shot to the devil boss. In between, of course, dodge the shots and co. Should not be too difficult I think.

Defeat 6-8 bosses with equiped Cursed Relic

This is definitely the hardest part. You must defeat the bosses at least on regular difficulty. The problem is, with the Cursed relic you only have one HP and every time you press the firebutton or dash, a different shot comes out. That makes things really hard. All bosses on all isles count (for me). It is still unclear how many you need exactly. For some players 6 bosses were enough, other players needed 8. For me it was 7 bosses.

Fortunately, there are also a two major tips:
- With every 3rd parry you get a HP in addition
- There is also an official cheat from the developers that also gives you an additional HP. To activate it, you have to turn in a circle / spin around on the map very quickly. Once you have finished the game (main or DLC), you can use the cheat on each island infinite but if you have neither the main game nor the DLC completed, you have only 3 wishes! on the specific isles. So be careful where you use the cheat. Once activated, the cheat remains active until you have defeated a boss.

With these 2 tips you have basically 3 HP, which makes the whole thing much easier. But it is still challenging!
You can see your boss progress by the Cursed relic, it changes appearance every two defeated bosses. After you beat 6-8 bosses you will obtain the Paladin achievement and the Divine Relic. Congratulations!

Video Guide

Since the other guides didn't mention this I thought I should make a quick guide about it,

Use a second controller!!

Since only Player one has the Cursed Relic equipped, the second player will still have full hp and have normal weapons!! I simply beat all the bosses in Isle I and some in Isle II to get this achievement.

Hope this tip helps you, good luck with your achievements.