End game Unique weapon enchantment

So as in Minecraft, we combine Power 4 bow together to make power 5. I am surprised we can't do the same thing and lose level along with the enchantment point (it should be bloody expensive).

For example, a level 110 unique weapon have the first level enchant on them and if you got the same weapon with +- 5 levels different you can add them together and make one weapon with 2nd tier enchantment on it and of course for the 3 enchantment below, we can keep either one from the weapon (no mix-allow) [The purpose of this is just to make your weapon unlock four 3 tier enchantment now make better enchantment to keep the grind ].

1-tier + 1-tier = 2nd tier unique weapon      (10-50 levels) consume base on weapon power

2nd tier + 2nd tier (or + 2nd tier) = 3rd tier unique weapon (100-200 levels) consume