I THINK what the OP is referring to is custom designed weapons, not the assortment of weapons we have now.
Those of us that have played NWN and some other games have an idea of what this entails (a point system that you use to tailor custom made weapons/armor/etc. to your needs).
Example: Taking a Legendary Broadsword (say 8 design points), adding Fire to it (another 4 design points), and giving it a higher chance to crit (+10%, 2 points). Total cost 14 points. I'm just pulling numbers of the air here, but this is how a crafting system works. In this game, of course you'd tie Crystal and other resources to the design choices for a given weapon, as well as the 'design point system'. You would then tie a 'design point cap' to the tech tree, so say you only have 5 points for custom design when you research Custom Weapon 1, 8 points when CW2 is researched, etc. CW1, 2, etc. would be tied into existing techs on the tech tree, or perhaps a new tech or two might be added.
The Combat Tree could increase the max attack strength available for custom weapons (still point system based though), while the Magic tree would increase magical abilities available via customization.
That may be too involved for this crowd though! But this does tie in to the wide disparity between weapons and armors currently available in Elemental. If there was a point system behind how the weapon abilities were picked, then we'd see a little more uniformity between them. Note the discussion recently about Masterwork Chainmail vs Masterwork Plate vs Regular Chain and Plate in another thread. Sure, we can tweak those values after the fact, but a 'design point system' would be another way to balance the pros and cons.