I did the coifs at level 20, and got 30 diremite webs, leveled up, and it went to crystals. Then I came back at level 27 and had all of them giving diremite webs. I turned them in and it went back to crystals. I have one level 25 one for 11 diremites and 1 slops, going to turn that in and see if it switches rewards at all.
Right now, I think rewards have a chance to change every time you level up, or turn in the leve.
I was doing the Coif of Gathering, and was getting Diremite webs. Then it turned to shards.
I switched to Fisher and turned in a few leves, and leveled up. I checked the Handcraft leves and sure enough, the Coif of Gathering was back to Diremite webs for a reward.
I switched to Weaver and completed it, got 30 more Webs, then I turned it in and it switchedto shards.
Looks like right now every time you level up it shuffles the rewards. And every time you get the leve on your list (by completing it and having it relisted), the reward is shuffled. I'm not sure what the percent chance is for it to be Diremite Web or Shards, but so far it doesn't see to be favoring one or the other. I've got about 200 Webs today from the leves there.
Every time I completed a leve, the rewards for existing leves changed. So I could keep doing leves until the reward for the 3 Coif leve changed to Diremite Webs.
Edited, Sep 15th 2013 7:06pm by TirithRR
Can't sleep, clown will eat me.