As from the patch notes, completing a weekly Archon Hunt will give you 1 Shard. When Kahl's shop opens up, you can only buy 1 a week from there as well. The problem here is being restricted to 2. If DE increased the amount to 5 a week, that would then take 50 weeks. A whole year of farming Shards is still a long time, but making it take over 2 years to get 5 Shards for every Frame is just way too long.