No. This is the most intuitive way to fit that much depth into the game while still letting the player process it slowly enough that they can make good decisions in game. What about putting in the tooltip what attributes of an item can be increased? So underneath the bonuses it gives you immediately, it has in one color the tier 2 upgrades and in another the tier 3 upgrades. Does this even make sense?

I like it, imma go photo shop my skill trees idea now!

No no no..  I said 24 STARTING items. (3-5 per category, average of 4.)  Consumables wouldn't have this.

It's 72 in the end, at the final path.  (24items*3 final paths=72 fully upgraded items)

This is certainly interesting but I think it is still too much.  I'd prefer giving each item a single upgrade path that just increases all of its attributes as Mehve said.  Then you can split up the attributes based on the type of item - boots increase speed and attack speed, breastplates increase health and armor, etc.  To make the different boots different, you give them fun things like thorns or stun resist or negative things like decreased crit chance or less health.  That way you can quickly say "ok, I want to move faster, so I pick a boot, and I don't want to lose anything so I'll just take the basic one, and oh! I got some more gold so I'll upgrade it once so I go even faster".  Buying a "level-2 boot" would cost slightly less than buying a level 1 boot and upgrading it, I think.  This way it is very quick to get what you want, even if you haven't memorized the item lists yet.

I think that the added flexibility of having an item possibly modifying three attributes (and it'll say it will in the store tooltip) will outweigh the few extra seconds it takes to read the descriptions in the store. Providing the opportunity for flexibility later in the game will allow less formulaic builds because you can follow the game better. It will allow much more unorthodoxy in design because you can adapt as the game progresses far more easily so you can take a dangerous choice without having your build become steadily more extreme as the game progresses.

My way does that too though, since instead of boots, a helmet, and gloves boosting energy, only ones does.  There would be 3 or 4 of each type to add some variety but you would still have fewer items altogether. 

No, instead you would pick boots for one attribute and a different type of item for the other attributes.  Or you could just accept that you can't have everything, which you accepted to begin with since you have to pick a Demigod that is only good at certain things.

Then I can't pick two high armor items?  That doesn't sound fun to me..

Plus I think a big part of what matters is that it's cool.  The branching upgrades would be cool. :]

I think after someone upgrades their first item, they'll understand it for them all and be able to just hover over the other items in the shop and be able to make informed choices.

I wouldn't mind any way but my prefered way is:

Each item has it's own upgrade path.(1-3 levels)

The movement boots could start with the 10% move for 500 gold, 15% for an additional 500, and 20% for an additional 1000. All the while increasing the armour the item gives by like 10% per level. Artifacts could get better and better activateable abilities.

It would also eliminate looking for the the plain higher level of what I already have thing and allow for more room for more unique items. (there are 2 breast plates which give health, 2 rings which give lifesteal, ect.) with out creating too many end items, with less clutter, ect.

I think since they are artifacts, they should do crazy stuff already.  Think of them as basically upgraded items that famous people used before they died, that are now available for you.

innociv.. you impress me yet again. i remember when I 1st started reading alot of your post I disagreed with alot.. but this is impressive. well thought out

I'm sold already, I love it, I'm just trying to come up with something to refine the internal workings. It is true that there is a fair amount of complexity, and making that complexity appear simple but deep is key to making it work properly.

Nice idea innociv!!. I got some more idea to share too. How about there's 1 upgrade blacksmith that do as you explain, upgrades things. But i think starting with basic gear that has no stat boost at all and start upgrading from zero is better, no need to buy any base item at all. This way it'll become like a skill tree with gold instead of exp. But it will reduce the complexity to choose between every base items and have to consider all upgrade paths and stats. 

Now for additional idea, how about we have 1 more shop, to add 1 "special passive ability" to items. Like you choose a boot, and add life stealing on it or choose a helm and add reduce cooldown. Just add those "Passive" things on it, to reduce complexity of the stat upgrade tree.

And for another ultimate shop, add 1 "active skill" to your items. This way we can throw away the Artifact shop and just put this shop instead. Less items with the same result. Of course this active skill upgrade should cost more gold to do than PASSIVE and normal stat upgrade.

This way people will have it easier to get what they want. Let's have a look at the example :

1. i need some thing that boost my armor!! ---> go to stat upgrade shop to get upgrades in armor branch.

2. Damn i can't run away from my enemies, i need teleport!! ---- > go to Active skill upgrade shop and get blink upgrade on one of the item

3. our team lacking in overall damage, what should i do?? ----> go to Passive skill upgrade and get +Damage Aura upgrade.

And for the dev team, it's easier this way since we no need of new items and unique skill tree upgrade for each items, just 5 trees for stats (1 for each type helm, boot, armor etc.) 5 sets of passive skills to upgrade (1 for each type same as for stats) and 5 more sets for active skills.

Why having different sets for each type of item? That's for balancing purpose. Say, you can't make all your items have +25% walking speed, or you can't have all Active chain lightning for 5 of your slots to spam (making it have the share the same cooldown just make it frustrating for new player that think they can make uber chain lightning spam).

Hope these idea help out