My first thought was to buy some kind of extra boost. May it in terms of extra units slots, earlier unlock of units types, or an one time boost for a single battle, but I quickly remembered Panzer Corps and how mechanics that rewards good players makes them even stronger, causing a run-away effect.
So I think glory should provide a something that doesn't necessarily leads to an imbalance down the road.
How about glory unlock special side missions?
High glory puts you at spotlight for supreme command. "Your continued success bought you the attention of high command and Commisar Yarrick himself. They think you're the right man for series of special tasks."
High glory will "reward"(burden) you with the optional playing of highly dangerous missions that have a unique touch.
The high difficultly of these mission should make it unlikely that you end up with bonus requisition. If at all you could very well loose some requisition, but still can valuable experience for your troops, beside the joy of playing an additional mission.
That way you can reward players for earning glory, but at the same time avoid this dreaded run-away effect that makes strong players get even stronger.
I expect Kerensky will object, as this throws work at his direction.

Edit: To further build on this idea. You would unlock missions at certain glory levels. The mission would always be the same. If you're a very good player earning a lot of glory, you will unlock these side mission very early, and as twist have to play them with a less developed core. Extra bonus difficulty! While a not so good or even struggling player which unlocks these missions later in the campaign, will have actually an easier time because of the more powerful units available to him. This would give the whole thing an automatic balancing. Side effect is that a not so good player would not earn enough glory to unlock all side missions before the campaign ends. This could basically be some kind of challenge tree.