I measured the effects of Nymeia's Ward over the course of gathering from 100 nodes. I got bonuses a total of 39 times, from 32 of the 100 nodes. (The difference is because 7 of the nodes gave bonuses twice.)
It was a +1 bonus twenty-six times, +3 five times, +4 three times, +6 twice, +8 once, +9 once, and +10 once, for a grand total of 92 extra shards/crystals over the 100 nodes where I was tracking it.
100 nodes isn't really a very big sample size, so the results don't give a very exact prediction, but if you figure you'll get an average of around one extra shard per node once you reach level 42 and earn that trait, you'll probably be in the right general ballpark. Not bad for a free trait.
