2. Tier System.What it means "Tier"?
Tier - technically, this is a Item level, but there are differences.
Level - associated with each character level.
Tier - associated with a character level interval.
Char 1lvl - Item 1lvl - Tier 1
Char 2lvl - Item 2lvl - Tier 1
...
Char 53lvl - Item 53lvl - Tier 6
...
Char 78lvl - Item 78lvl - Tier 8
Etc.
Why I plan to use Tiers?
Well, I think it's more convenient. Require less time to create all necessary items. There is no need to do a "Long" 100lvl - graphs.
Moreover, a player is likely not notice the difference and I will explain why.

Now, the original system is "too overloaded". We have a lot of items, but they are not much different.
Let's say we have two different axes -
Axe lvl5 & Axe lvl6.
Axe lvl5 have 120-125 damage
Axe lvl6 have 125-130 damage
- difference is insignificant. Player does not have incentive to seek a second Axe, because it is almost identical to the first one.
But if we look at other two axes -
Axe lvl5 & Axe lvl10.
Axe lvl5 have 120-125 damage
Axe lvl10 have 145-150 damage
- now we see a significant difference between these Axes.
Therefore, we do not need intermediate variants. We just keep and use Axe lvl5 & Axe lvl10. Gap between levels we will fill using the "rarity". Characteristics / bonuses: Rare Item = 1.2 Normal Item, Unique Item = 1.4 Normal Item
I plan to use 50 character levels, so I use 10 Tiers.
Tier1 for 1-5 Character level
Tier2 for 5-10 Character level
...
Tier9 for 40-45 Character level
Tier10 for 45-50 Character level
This is handy - for each Tier will match its own parameters(armor, damage, bonuses), icons and 3d-models(we have about 13-19 models for each type of weapons and armor. 10 we use for Tier1-Tier10, the other for unique items).
Also, I removed all information about item level. When you find an item, you can not know what level has this item. I believe that this information is not critical and only distract from important information.
Items without level - it is very convenient.

For example, you can put a Normal high-level Item in the the starting location.
Yes, is a Normal Item, but has high characteristics.
If the Player will see information about level of this Item, it may arouse suspicion
-
"Why I find an high-level Item in a low-level location? Maybe it is a bug or cheating?" -
"Nope, you just found a Super-Mega Сool Item!" But we do not have information about the Item Level and now it's not a bug - it's a feature that allows us to create and use one Item(Normal high-level Item) instead of two (Mega Cool low-level Item & Normal high-level Item).
Something like this:

You can see that Normal Axe Tier3 much better than Normal Axe Tier1 and without information about the Item Level you can use it.
to be continued