working with Hitori Hanzo

Over at the Scion forums, I'm trying to brainstorm a system for making super-tech and Hitori Hanzo steel. Others started the ball rolling on this, but I had issues with the system they were proposing. Here's draft #2.1.1 of the extended roll version that is my counter-proposal:

Roll of: Dexterity + Craft if trying to make something finely balanced or incredibly sharp. Intelligence + (Craft or Science) if trying to build a better mousetrap. This is an extended roll, with the following stats:

Roll interval: 8 hours.

Cumulative Difficulty: based on the value of the item in Relic dots. Something like this:
1-dot-Relic: 20 successes.
2-dot-Relic: 40 successes
3-dot-Relic: 60 successes
4-dot-Relic: 100 successes
5-dot-Relic: 140 successes

Individual Difficulty: Equal to the dot-value of the item you're creating. That gives 1 success towards the cumulative. Threshold successes also cut into the cumulative.

Assuming Hitori Hanzo has a 14-die pool (He's a Legend 1 mortal, with Dex 4, Craft:Swordsmith 5, 2 bonus dice from his excellent furnace, 2 bonus dice from his masterful tools, and 1 die bonus from the Limited Teamwork provided by his apprentice)... He would need to roll about 46 times to make a 5-dot relic sword. So, realistically, he could make a sword like that every other month. With an individual difficulty of 5, there's a decent chance he could botch one of the rolls and have to start over. He's got one point of Legend, so he can reroll or Deed once during the process. (Though he can get more temp legend to fuel rerolls by stunting - turns out that's why he was such an eccentric character in Kill Bill).

To make a mere one-dot sword takes him 3-4 days of work, and he is extremely unlikely to fail.

Planned improvements to this system:

• This system still needs a good deal of tweaking to represent the actual relative power-levels of Speed vs Damage vs Defense vs Accuracy vs Range. Anyone who has built (and then used) a Relic weapon in Scion knows those stats are not equally-valuable - I'd guess it's roughly in the order listed, with Speed being the most powerful. Various armor and vehicle traits could also apply, with all (save Agg Soak) falling somewhere after Accuracy.
• I'm also tempted to change the roll interval to 24 hours, thereby allowing a roll every 3 days for a mortal, or every "all-nighter" a Scion pulls. This would slow down the process a lot, hopefully with the effect of reigning in things a bit at the Demigod level. I have a PC in my game currently, who could work round the clock for 4 days and score a 5-dot relic in about 13 rolls - far fewer rolls if she uses Deeds and Channels. The solution to that is either a longer roll interval or a higher cumulative difficulty. I think the cumulative difficulty increase is more balanced, but who really wants to roll even 13 times to complete a single action? Need to play with the numbers a little till I get something I'm happy with.