Eotn Items only drop dungeon endchest

That's about it I think

the singing blade is not missing. from what I see it is mentioned on the page below that it can drop from multiple dungeon chests, thus it is not assigned to individual dungeons.

Darkhorn rod, agree

onyx staff

legendary sword

runic blade

pyroclastic axe

diamond aegis

demon tongue scythe

those I found all on wiki - just go to the wepon pages (e.g. staff) and go by the ones for EotN. the check their entries on where they drop in the discussion pages as well as on the main pages. I won't guarantee anything, but this is what I found - and I might have made mistakes in either direction

diamond aegis is a bit disputable since apparently in eotn it does only drop from endchests, whilst on other campaigns it comes as well...