I want to pump up the group I'm GMing for with Mythic rules.
There is a warpriest in the group, and I wanted to have him earn the privilege of wielding the holy weapon of his church and make him a mythic champion.
My main problem is having this weapon to be powerful all along the campaign, without feeling like I gave him a +10 weapon at level 5. I also need that extra kick of potential to be accounted for in the mythic path. I have found this universal path ability:
Legendary Item (Ex)
You gain a legendary item. This item grants a number of abilities equal to your tier (maximum 3). At 3rd tier, you can select this ability again, increasing the maximum to six abilities and causing the item to become a lesser artifact. At 6th tier, you can select this ability again, increasing the maximum to 10 abilities; the item then becomes a greater artifact.
But it is very vague and I don't know the creation rules of this item.
However, I only own the core books, and I'm lost in the rules of d20pfsrd.
What are the relevant rules for creating such an artifact weapon?