Guild Wars 2

I just done a part from the new story and as a reward it would give me a Golden Strap, said to upgrade my new backpack earned in earlier HoT story.

However, nothing happened and it just disappeared upon receive..

What’s that about?

Those items are trophies, and never end up in your inventory – at least not the ones rewarded from the storyline. You can check them in Achievements > Collections > Basic Colelctions > Crusader’s (or your choice in pack) Pack.

They’ll be highlighted there, which means you’ve unlocked them. Hope this clears it up!