Dodge

At level 19 this enchant gives 2% dodge, same as a lvl 34

This can still be applied to 19 twink gear as of patch 3.2.0 despite saying it requires a lvl 35 or higher item. (successfully applied to an ilvl 24 cape)

So how much dodge does this grant at level 70?

It's about 0.63%.

When tanking your other option is 120 armor which might be worth slightly more, but doesn't provide anything to reduce crushing blows.

When I say it helps reduce crushing blows, I'm mostly thinking of paladins and druids. Every point of the attack table spread covered by dodge contributes to the 102.4% needed by paladins to completely avoid crushing blows. To do this requires a significant level of gear. For druids, every percent of dodge is that much less chance to be hit by crushing blows. For warriors whose attack table is covered by the Shield Block ability (given a high enough dodge/parry/block/miss total), the value of dodge is in its hit avoidance and preserving Shield Block charges, and less in its ability to "push crushing blows off".

That being said, Druids should never take this enchantment, and should take 12 agility instead. See the page for that enchant for reasons.