This might sound dumb, but this line of thinking does not come to my brain as intuitively as it does for others. Same with re-rolling weapons. I don't know how to work the system in my favor. I'm not good at playing the game inside the game. I've never re-rolled, I've never ascended anything. I know this sounds rediculous, but back when there were all different types of energies and shards for upgrading I rarely had the necessary materials, coupled with my limited play time, I avoided using them on weapons altogether. I knew the DLC weapons that were coming were mostly already better than anything I could waste my time and materials upgrading.
I tried using some materials on armor but quickly realized the futility of wasting these materials when none of my armor was raid acquired. I would never get to a high enough level, and I probably never will. I've got a handful of these old materials from the past in the vault still.

The situation at hand is:
I have an original Pocket Infinity that is fully upgraded, short of ascending it. 300 Attack
I just finished the exotic bounty for the Pocket Infinity that I've been toting around for months. It has no upgrades yet but Attack 334/365.

What is the best strategy to take here?
I have *A* Exotic shard on hand and could ascend the original. Won't I have to just upgrade everything again?
Do I start slowly upgrading the newer Pocket Infinity since it is "ascended" already and Shard out the old one? Will I get 2 Exotic Shards for the fully upgraded old one?