Artifact weapon question

I am planning my second pathfinder character with my gm. He is a Sulis Titan Mauler Barbarian and long story short very far down the line my character finds out he's the son of the recently murdered god of lightning. At this time my character gets a weapon that I've been working on called "Scepter of the Lightning Lord" or a +5 giant-bane thundering maul of the titans with the ability once per day to cast Call Lightning Storm.

Now my question is is this weapon to powerful? what level would you allow it in your game? If you have a good idea for this weapon I would love to hear it.

Thanks!

Well going by abilities of the weapon(mind you this is mostly guesswork):

+5 Enhancement, Bane(+1) & Thundering(+1)
Effectively a +7 weapon ~98K

Maul of the Titans ~25K(though one could argue reduced cost from wasted enhancment)

Daily Spell Ability w/ Command Word ~ 180K(5(spell)*20(CL)*1800) 18

~1.5 Cost for multiple enchantments

Grant Total: ~405K Item

Now is that OP? Its an artifact, of course it is. However, I'd say it's inline with Minor Artifact Weapons. Typically, I rate an Artifact as "Major" if it's abilities would be worth over half a Million in costs. Not to undervalue it, it's just no Axe of the Dwarvish Lords(my benchmark for those kind of items).

Now when would I let my players find it? Level After level 15, and that's taking into account I play as high magic as heck in my games. Reason is, there's very little barrier to using this item. Martial characters will have 18 STR by level 4, if not sooner assuming they have decent buy/rolls.

Darth,

Away from book but you forgot to divide by 5 on the Daily spell ( to get it only once a day) so instead of 180k you are talking 36,200.

Enchantment after first is *1.5 not all.

If memory serves maul of titans just gives size but is a +3 weapon so 25k - 18k = 7k (really not sure on this part but as I said away from book).

A more reasonable price would be 98K + 7k + (36.2 * 1.5) or 160k (rounding).

No it is not too powerful but again I would not really expect it before level 15.

Ah, I was away from my books as well. My bad? Doesn't matter much much though, just means my own personal metric my need to be adjusted.