So far I've upgraded:
1. Efrideet's Spear
2. Jolder's Hammer
Upgraded those mostly due to the amount of PVP I have been playing lately - Trials of Osiris and Iron Banner.
I currently have a few Etheric Light stashed away, but I am still debating on which of the raid weapons to upgrade. Blackhammer is definitely top on the list as I have not been lucky enough for a Fatebringer to drop. :(
What's on your list?
Edit:
Went on a Etheric Light spending spree and ascended these:
1. Vision of Confluence
2. Black Hammer
3. Fang of Ir Yut
4. Word of Crota
5. Found Verdict
6. Praedyth's Revenge
7. Swordbreaker
8. Hunger of Crota
9. FATEBRINGER! (Dropped yesterday - 06/14/15, ascended before leveling up)
My reasoning for ascending raid weapons before vendor weapons is the fact that I will not break these down for any reason - they have great perks and they are versatile for burns in Nightfalls, Prison of Elders, and other activities.
Also I only ascend one copy of each weapon since I use Destiny Item Manager for loadouts.
-
Fatebringer, Vision, and some arc rocket launcher I don't remember the name that I got a great roll with.