How to put invulnerable item?

[Umokthar]

I got my blue dragon scale amor and i wonder how do i make it invulnerable?

[Laith]

it is already bound, thus it cannot take permanent damage.

all items take damage from death and wear though. you can repair dragonscale with cash in meridia or relics in gianthold.

if you want it to take repairable damage slightly slower, you can use the Adamantine Ritual (link).

[Corvid7]

I thought bound items could still take permanent damage unless you do the attuning ritual with the khyber shards... am I wrong?

[Comfortably]

I thought bound items could still take permanent damage unless you do the attuning ritual with the khyber shards... am I wrong?

Yes you are wrong, a bound item will never take any permanent dmg.