The color rating does help groups narrow down what items they want to get and what to ignore. I'm sure most players would skip reading or considering anything below black - which makes it / contributes to making it difficult to convince them to get something purple.
Purple just seems like an awfully low rating if the only thing holding this back from sky blue is if you have the group where that is possible - the items aren't even rare (unlike fortune stones) and those got a gold rating all the same.
I'm thinking at least blue.
Note that you can stick the weapon into a gauntlet axe and that untyped bonus to hit (and damage) = STR / CHA +2 can possibly negate the need to re-roll anything other than a 1 for those with the right stats. Apples and oranges of course, free action re-rolls if you need it is still a great safety net.
Hope this helps MwaO.
