why does enchanting an item with a higher enchantment end up with a less enchant than original

geosto1b16_ESO2

when I enchant an item to raise it from 300 to 400 for example, I end up with an item enchanted lowered to 150, this makes no sense at all and with no notification the enchant glyph is lost.. the item should be classed none able to enchant (because a reduced outcome for a higher level would be deemed unwanted), to use a lower enchantment to lowwer the original and end up with lower enchanted item could be ok to do , tho' one would not see the reason why one would do that.which begs the question, why did some software developer think it OK for this outcome to happen what logical reasoning would they think this?

FloppyTouch

Small pieces of gear cuts the enchant in half large pieces get the full enchant

PlagueSD

Um, you see the preview tooltip before actually applying the enchant. Maybe check that before actually enchanting the item.

Dubhliam

Small pieces get half the enchantment value.
Those are:
Feet, gloves, belt and shoulders.

As suggested, look up the preview tooltip before proceeding with the enchant.

baratron

In addition, you can basically assume that any dropped gear comes with an enchantment equal to the colour of the gear. (I think this is always true but there may be rare exceptions). Therefore, if you have blue dropped gear and you're trying to put a green glyph onto it, you will always get a weaker enchantment than what was already on it.

Mind you, dropped gear has its enchantment upgraded when the item itself is upgraded, as long as you haven't changed the enchantment it came with.

Crafted gear can have any level enchantment or none on it, and these enchantments DON'T get levelled up when the gear is improved with tempers.