I'm not trying to limit damage or whatever as much as I am trying to create some sort of progression. I'm mostly working with the storyline, but it would be kinda strange to have any progression at all if there are already godlike weapons going around.

They'll come, not quite yet though.
The basic trader items are weak on their own, that's why there are augmentations and other things. Also, as a trader maybe you don't want to create quantity, but instead quality? There aren't a ton of players right now, really not that many. If a trader were able to create two or three super weapons every four days everyone would have one. Perhaps try one weapon of the greatest power you can make per every four-day period? I am trying to time things out so when the end of the storyline comes, traders will be making the best equipment.
Also, I think there may be confusion with what is weak and strong in this since a few quests and whatnot put things off balance. You're not supposed to be running around with a post count of 100 with a weapon that can do hundreds of DP per hit, lol. That's what Strength is for, as you increase in power so will your weapon. The same goes with augmentations if they are obtained. This prevents someone with a post count of five potentially being able to beat someone with a higher level. Even without spells and with the same equipment, one Paladin with a post count of 100 will be obliterated by a Paladin with a post count of 4000. That's where I'm trying to take things, not insta-kill weapons everywhere but weapons which will become more effective as a character grows in strength.
This will also prevent, for example, a Sorcerer from slaying a Paladin without magic if both have the same weapon. Wouldn't make much sense.

Credits are Corrorian currency, and Cinii are currency for everything else.

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Addition:
Here is the system working, hehe. You have a strength count of 94. With that on top of the Mythril Longsword you made...
You would do 505 damage per hit without any abilities, stat enhancements, or anything else. That is comparatively a lot, lol, especially when taking into account the fact that you can just pound 505s out of someone without any EC or effects on battle speed.