[Question] Need help with spell dagger mechanics

I have two spell crit daggers that i paid vastly different amounts for, but am seeing the same tooltip damage.

I purchased "Morbid Edge" awhile back for ~20c

http://imgur.com/5HVdGXx

Then more recently I saved up and paid 70c for "Storm Fang"

http://imgur.com/wkqjpsN

When I purchased the Storm Fang, I was ignorantly thinking that the high base crit was going to boost my spell crit chance, forgetting that spell crit has nothing to do with the base weapon crit. As a result, my tooltip damage actually went down slightly from 23,619 to 23,443. This is with 2 heralds, no charges or other buffs. The difference makes sense considering they are pretty comparable, with the only major difference being the implicit Crit Chance and the Increased Crit Chance mod on the Storm Fang.

What i'm trying to figure out is why the price difference is so crazy. At the time i purchased both daggers, they seemed pretty comparable in price, crit multi, and spell crit to other daggers available for trade. Is there something in the mechanics of global crit that i'm missing that makes Storm Fang so much more expensive, or did i simply get a good deal on one and a bad deal on the other? Thanks for any input.

Oh, and I'm playing low-life spark on a 5-link, for what it's worth.