What I said in the tittle… any Arc Explorer for GD?
Use asset manager to extract all the assets, no need for arc explorer.
Where is the option?
I recommend reading the Modding Guide (PDF file) included with the game.
It explain all the steps. I don’t want to sound like an asshole by saying that, don’t get me wrong
In the Asset Manager, you will go to Tools and then extract base game files.
tl;dr
Tutorial 01:
Asset Manager
This tutorial covers the Asset Manager and creating a new mod. Before you can work on a mod, you will need to launch the Asset Manager to perform First-Time Setup. You will also want to Extract Core Game Files so that you can access the game’s default templates (for the creation of new files) and database (for referencing existing game files).
First-Time Setup
When you start up the Asset Manager for the first time, you will be asked to create a Working and Build directory. These are set to the game’s installation directory by default so that the World Editor and other mod tools can load the default game assets. If you choose to change the Build directory, note that your tools will not load the game’s assets and will instead load only assets you create in your mod.
Extracting Core Game Files
Chances are that you may want to make a mod that alters existing game data rather than creating something entirely new. Or perhaps you just want to take a peek under the hood and see how certain things in Grim Dawn were made.
To facilitate this process, the Asset Manager is capable of extracting all of the game’s database, template and asset files for reference purposes. Template files will be critical to creating new game records, such as items, monsters and skills.
Database records and templates are extracted to /database while assets are extracted to /resources.
To extract game files,
go to Tools -> Extract Game Files and select the Grim Dawn installation directory (default: C:\Program Files (x86)\Steam\steamapps\common\Grim Dawn).
This will overwrite any existing files in the /database and /resources folders, so do not run this process if you have files in there you are working on. This will rip all of the records, assets and template files from the core game archives.
Note: this requires at least 5gb of additional storage space on your hard drive as you are extracting compressed game files. This process may take several minutes during which the Asset Manager may become non-responsive.
If these files are placed within your mod following the same folder structure as the base game (ex. database/records/items/gearhead/a01_head001.dbr), then any changes you make will overwrite the original file while you are running your mod.
By the way some of the files are getting bugged because of that.
For example: If I extracted the database and making changes to gameengine.dbr in my mod, I will need to rename or remove …\Grim Dawn\database\records folder to be able to see any changes.
true!
Like PrincessLuna stated, if you want to modify for example the skill of class06 (Shaman), you will need to rename the skills or remove them from the base files.
Easiest way in most cases is to rename them.
If you have more questions, just reply 
Thank you Mur… I have to print it in order to read it comfortably…