Under C:\Users\[Username]\Documents\Fell Seal\saves you find what you need.

Files:
"slot-1.sav" and the likes are the autosave files.
"slot01.sav" and the likes are the manual save files.
Open your preferred one in NotePad or a similar product, and browse through your shopping list.

Examples:
<mGold>715713</mGold> The game saves your money here.
Between <CharacterData> and </CharacterData> you will find all stats for one character. <name> indicates, who it is.
In this block, you will find AP per Job to unlock abilities, level, equipped passives and counters, realspeed i.e. placement in combat order, statbonuses, and most important of all: <realHealthMaxNew data="125.25,34.95" />
In this row, there are two nimbers that may be decimals, but need not be. In my example, it's 125.25 and 34.95.
Change the first one to 999 and the second one to 500 and your character will live longer. Warning, because there are many %-damage abilities, so your newly buffed char may still take 200 dmg from one swing, and you cannot heal that fast. Not much of a problem, mostly.
If you know the right codes (I don't yet) you can even change your world map location and your story progression, or the treasures you found!

If you are a bit code savvy (and I didn't have the time to look into it yet) under C:\Users\[Username]\Documents\Fell Seal\customdata_examples you see many-familiar-words.xml files. In here you can make the magic work. I am pretty sure, that, after the first upgrades through shops, you might be able to set the starter weapon damage to 999 and swing away with your wooden swords, while enemies use higher tier weapons with normal stats. Just hope, you hit the one guy with his tutorial sword first...

HAVE FUN AND EXPERIMENT