Your save file will be located in the LocalLow subfolder in the AppData folder. Here's how we reach there:

• Press "Win"+R to open the Run window.
  
• Write "appdata" and run.
  
  
  
• Open these folders: LocalLow > RedHook > Darkest Dungeon II > SaveFiles > *numbers* > profiles
  
• Here, we will be editing the "profile_1.json" file. It will be named with the order you created it. "profile_1.json" will be the name of the first profile you created. Here you can see the files in my system:
  
  
  
• Here, we can find the unlocked heroes, paths, trinkets, stagecoach items and unlocked stories for all the characters.

Now it's time to edit some sections. Depending on what you have unlocked, what you need to do may differ. I have not tested some of these things and will clarify them when needed.
You will need a text editor like Notepad++[notepad-plus-plus.org] or Visual Studio[visualstudio.microsoft.com] or some kind of code editor that can edit json files to edit these files. I tried both, I'm not too knowledgeable about this but if you use these you will not have a problem. I recommend Notepad++ because its a small program.

• SAVE EDITING IS INHERENTLY DANGEROUS! TAKE A BACKUP OF THE FILES YOU'RE EDITING TO UNDO YOUR MISTAKES. BE CAREFUL.
• THIS GUIDE ASSUMES YOU HAVE "THE BINDING BLADE" DLC INSTALLED! I DON'T KNOW WHAT HAPPENS IF YOU DON'T HAVE IT INSTALLED. TRY TO SKIP THE LINES RELATED TO THE DLC TO AVOID CORRUPTING YOUR SAVE.

This section will show how to add the skills to already unlocked heroes. If you have not unlocked a hero and add their skills, this will not unlock them. (You can find how in the later sections.)
To add the skills, we need to find the "m_UnlockContainer" section. It looks like this:


We will be adding the lines that the Shrines of Reflection would add here. The commas at the end of the lines seperate each entry so the last one in this section should not have a comma at the end. If you're using VSC or some editor like that it'll probably notify you that there's something wrong with it. You should save this file only after making sure there aren't any errors.
Each hero's skills/story can be found below:

• Plague Doctor
  "herostory_PD_01",
  "herostory_PD_02",
  "herostory_PD_03",
  "herostory_PD_04",
  "herostory_PD_05",
  
• Graverobber
  "herostory_GR_01",
  "herostory_GR_02",
  "herostory_GR_03",
  "herostory_GR_04",
  "herostory_GR_05",
  
• Highwayman
  "herostory_HWY_01",
  "herostory_HWY_02",
  "herostory_HWY_03",
  "herostory_HWY_04",
  "herostory_HWY_05",
  
• Man at Arms
  "herostory_MAA_01",
  "herostory_MAA_02",
  "herostory_MAA_03",
  "herostory_MAA_04",
  "herostory_MAA_05",
  
• Leper
  "herostory_LEP_01",
  "herostory_LEP_02",
  "herostory_LEP_03",
  "herostory_LEP_04",
  "herostory_LEP_05",
  
• Vestal
  "herostory_VES_01",
  "herostory_VES_02",
  "herostory_VES_03",
  "herostory_VES_04",
  "herostory_VES_05",
  
• Jester
  "herostory_JES_01",
  "herostory_JES_02",
  "herostory_JES_03",
  "herostory_JES_04",
  "herostory_JES_05",
  
• Occultist
  "herostory_OCC_01",
  "herostory_OCC_02",
  "herostory_OCC_03",
  "herostory_OCC_04",
  "herostory_OCC_05",
  
• Runaway
  "herostory_RUN_01",
  "herostory_RUN_02",
  "herostory_RUN_03",
  "herostory_RUN_04",
  "herostory_RUN_05",
  
• Hellion
  "herostory_HEL_01",
  "herostory_HEL_02",
  "herostory_HEL_03",
  "herostory_HEL_04",
  "herostory_HEL_05",
  
• Flagellant
  "herostory_FLG_01",
  "herostory_FLG_02",
  "herostory_FLG_03",
  "herostory_FLG_04",
  "herostory_FLG_05",
  
• Crusader
  "herostory_CRU_01",
  "herostory_CRU_02",
  "herostory_CRU_03",
  "herostory_CRU_04",
  "herostory_CRU_05",
  
• Duelist
  "herostory_DUL_01",
  "herostory_DUL_02",
  "herostory_DUL_03",
  "herostory_DUL_04",
  "herostory_DUL_05",

If you paste these lines to your unlocks section, all the skills for that character will be unlocked!

To add candles find the section named "m_ProfileValues". Theres only one value under it named "candles". Be careful not to edit the "m_PrestigeProfileValues" or the candles spent on each hero.
To change the current number of candles you have when you reach the Altar of Hope (by losing/winning a run only you can reach it) you change the candles value there. It looks like this:


Right now there's 0 in mine. There's one decimal place, don't change that one. Write whole numbers, avoid negative numbers too.

Now, unlocking all these seems to have an additional step to keep things stable. I don't want to test what would happen otherwise so let's stick to the rules.


Since unlocking these things increases the candle tracker, we will need to change those values.
Firstly, we will add the items to the m_UnlockContainer's sub-list, m_Unlocks.
This is where the lines will be added (same as adding the unlocked skill lines):



Now, there's a whole lot of stuff here. Pasting it here is impossible since it does not fit. This list will include ALL unlocked items. This means stagecoach, combat, trinket and inn items; weapons and armor cosmetics for the characters. Here's[github.com] the link.

Now you'll need to paste all these lines to the m_Unlocks sub-list that you can see in the image. Do pay attention to remove the comma at the end if there is one, I removed it in the github file. It should look like this:



Now we have unlocked every item to be available. We will need to raise the candle counters that unlock these items normally. Right below the m_Unlocks list, there will be another list for candle values. Before adding values it might look different. To add the candle counter to a fresh save, we will need to add these lines between the blue square brackets, just like so in the picture. Get your cursor between them, press enter and paste this:


The "53.0" is a placeholder. It will change between the members of the list.

It looks like this after values are added:



Now we'll need to increase each value to the ones listed below.

• "stagecoach"
  94.0
  
• "memory"
  85.0
  
• "resources"
  119.0
  
• "prestige"
  66.0
  
• "man_at_arms"
  53.0
  
• "highwayman"
  53.0
  
• "grave_robber"
  53.0
  
• "plague_doctor"
  53.0
  
• "hellion"
  61.0
  
• "leper"
  61.0
  
• "jester"
  61.0
  
• "occultist"
  61.0
  
• "runaway"
  61.0
  
• "vestal"
  61.0
  
• "flagellant"
  61.0
  
• "bounty_hunter"
  41.0
  
• "pets"
  85.0
  
• "infernal_flame"
  300.0
  
• "crusader"
  53.0
  
• "duelist"
  53.0

Now, all the previous sections assumed you had The Binding Blade DLC installed. I do NOT know what will happen if you dont have those. Probably something will, so don't blame me, I did warn you.

Now the Crusader quest's tracker is right below the candle trackers. Just like before, we're gonna paste some lines and it'll be done!

Find the "m_QuestTracker" list. It will look like this (if it's completely empty):



If you have partially completed the quest, there will be some of the lines between the square brackets. If not, place your cursor between the brackets and press enter. Then paste these lines there:

Now, if you want to unlock the Crusader ONLY and you haven't unlocked all items (like we did in the first section), you WILL have errors. We will need to add one thing to the unlocks list. For this, go to the sublist of "m_UnlockContainer" named "m_Unlocks" in the same file. It will look like this:



You will need to add one item, "crusader_quest".

Your "m_UnlockContainer" will look like this after.



And that should be it! This has worked for me twice in fresh saves. Just to make it a guarantee, I'm going to upload the last savefile on my github[github.com].
You should change the two #'s to an empty profile number AND change the name of the profile to your liking. Empty profile number means however many profiles you had +1. Profile name should be 15 characters max, spaces are allowed. If use more than 15, it is still displayed correctly.



Then just throw this file into this directory:

After that, open the game, enjoy your new profile with the quest over.

For this, I still had to do the tutorial expedition that ends after you reach the inn. You'll need to find the "m_BossSelectCounts" list right below "m_LastStageCoachSkin" value. It looks like this:



Now, we'll need to change two things: Boss select counts and Boss victory counts. Your whole selection should look like this:

Now, you can possibly add everything you want by editing this save file. This means every item, the Crusader quest, skins and weapons sets. Everything. You can even edit an ongoing run if you so please. I have done it and it works! I will add how to do that in the future but for now, with this small section I will be ending this guide.

And remind yourself:
Overconfidence is a slow and insidious killer.