Method to acquire Henrir's equipment would be easier to explain with a powerpoint presentation
Immediately, you may be able to deduce that there are 3 paths to take (in increasing difficulty):
1. purple - normal mode
2. beige - challenge mode
3. beige ultimate - normal + challenge mode
For paths 1 and 2 (they are not connected in any way), u need to craft by increasing level. namely;
lvl 10 gear can instantly be crafted (ruben card pack + secret cards), but lvl 20 gear would need its lvl 10 gear and other stuff (elder card pack + secret cards), lvl 30 gear needs its lvl 20 gear and so on.
You have to exit Henrir early to get the low level cards and you will be doing this quite a number of times as you need the rare secret cards from each phase (or you can just buy them; in this case you just need to clear the low areas approx. 10 times for the untradables).
You can craft the gear directly from NPC or craft the black (sealed?) ones. They are the same in terms of requirements and stats, just that you can't use the black ones but can sell them and vice versa for the gear directly crafted. Whoever who bought the black gear can exchange for the gear they want on your screenshot.
As for the final path... start after you finished a black (sealed?) 50 beige weapon. You have get card packs of all areas in both challenge and normal modes. Assemble them into world card packs then universal card pack and finally craft the ultimate gear in the game and claim you have beaten (read: hacked) the game.
Just for fun:
Assuming you clear henrir normal in 20 minutes and challenge in 30 minutes; God loves you (only all the cards you need are given and secret cards drop for you 100% of the time)... to get the ultimate weapon, you need to clock in only 14 hours (30 normal runs and 36 challenge runs, most incomplete).
In reality, you are very likely to get repeat unwanted cards. Farming for keys can take forever. Secret cards drop 10% of the time and you may have to share, you may want to set your ultimate goal at 14 months.
If you are uninterested in the above...
This NPC is for farming unknown elstones or stones for socketing, and also for buying 50mp pots.