I believe this item, along with many trade skill items became no longer used in the recipe. A very large across the board revamp of such items took place in this era.
Not sure about the temple, but I picked up 6 in about 2 hours hunting the zoneline in The Grey. The mobs in Ssar seem to drop Shissar Scales frequently though.
I wonder about them being magic - are they used for something? I'm surprised that vendors sell them, maybe it was because someone sold it to the vendor. I get over 19pp from vendors for these.
Some loot is marked "magic" and I believe that means it can't be pick pocketed by a rogue. Simple means of keeping sticky fingers for stealling all the good loot without killing. My understanding of rogues anyway, and I'm not the expert.