User blog comment:IamJakuhoRaikoben/Chapter 377 & 378: Imperial Wrath of the Heavenly Dragon & With Friends, Always, Review./@comment-17764746-20140329001023/@comment-7418318-20140329005620

"Ur who was said to be 10 wizard saint tier"

Ur was NOT on equal terms with a wizard saint. Siegrain/Jellal said that if she had survived, she might now (which is already seven years in the past of the current point of the story) be a wizard saint, but that was ten years later. Meaning if she had trained and grown in power for ten more years, she could have been equal to a wizard saint, but back when she cast Iced Shell she was still far from that level.

She even said that there were a lot of wizards stonger than her to the west. If you are one of the ten wizard saints, there aren't that many mages stronger than you.

Now for the matter of Dragon Force: When Natsu went into Dragon Force, it was because of massive influx of external energy (Etherion and Flame of Guilt) which he got in addition to his own magic power. And with Wendy it was the same, since she ate air enriched with a high concentration of Ethernanos.

Sting and Rogue on the other hand didn't get any additional magic power and had to use Dragon Force with only the power in their own bodies, so it's no wonder that they wouldn't be able to gain an equally big boost in powers as the other two.

Furthermore Wendy also had second origin unlocked. With being able to use the second magic container, she should also be able to absorb twice the amount of magic from that Ethernano-air, which would also explain why her boost in power from DF seemed to be bigger than what Natsu got in his two cases.

While I can understand where you're coming from, the situation is far less ass-pully than you make it out to be.