Omen of Refreshment should restore Flask when you are out of Flask charges.

It doesnt make a lot of sense for it to restore flask charges when you reach Low Life. It would be far better to have one option to restore flask when its empty. You can limit it to Magic flasks if you want. Some build rely on flask charges to deal damage or to sustain a fight with a boss. This Omen would help a lot. And you still would not be able to sustain it more than one time.