Well, well, well.
It's been awhile since this thread has had a costume item update. I'm honestly surprised this hasn't been identified yet.
Cruising through the archery section at my local Dick's Sporting Goods, I couldn't help but notice some arm guards that had a very familiar looking clip. Something like this...
Can you see where I'm headed with this?
There were 2 models of arm guard on the shelf. One had 4 straps. The other had 2 straps. Neither caused me to take a second glance. I bought the 4 strap version with the intention of cannibalizing the clips. Why not, right? The price was great.
So, I sent the following picture to
Primrodo to discuss the clips I had found.
A few minutes later, (I'm glad he decided to investigate further) he comes back with...
THE SEASON 1 FOREARM QUIVER/ARM GUARD/FLECHETTE HOLDER
Based on how crudely made (by the costume department) the Season 1 forearm quiver is, it is fairly apparent where the base came from.
Allen Company 3-Strap Arm Guard -
http://allencompany.net/archery/armguards-gloves-tabs/saddlecloth-armguard.html
The overall shape, strap location/material/construction, and the clips all point to this being the base used during the first season. Not to mention if you look at the super high-res pics from SDCC, you can see for yourself.
The hunt for the rubber shaft holders that were added to this is still on. My guess is they're right under our noses.
(The revised forearm quiver used since Season 2 was made from scratch, but patterned after this original.)