Hmm.a) (Pet Command) - "Refrain"
Description: "Restricts breaths but increases attack speed and accuracy"
Note: This would disallow Wyverns to use any breaths when the Dragoon uses a spell/weapon skill or breath command. It would increase the Wyvern's attack speed and accuracy thus optimizing it's TP gain. For hard NM fights this would be more useful than having the wyvern use breaths as it would mean more TP gain for the DRG.
From the perspective of a developer or game programmar (which I am not), I think I would find this overpowering. As it stands right now, not many Dragoons even like their wyvern's breath attacks since, barring Deep Breathing being used in tandem with it, they are oftentimes weak, and a waste of the wyvern's stored TP that most Dragoons would prefer to use for themselves via Spirit Link.
What I am basically saying is that while I see what you are trying to do, a "trade-off" sort of deal, I think this ability in itself is a little on the overpowered side of things. It's not really a trade-off when breath attacks are always disliked, and the amount of extra damage you'll be able to do from self-chaining thanks to Spirit Link TP would blow breath attack damage out of the water.
That and I also think it is nice that such Store Wyvern TP abilities are reserved for the DRG/Mages out there. It gives us a way to keep up, sometimes even outdo, the damage a DRG/DD sub can do, so long as we're not self-healing or got caught using a breath to cure a status ailment. :P
Edit:
I do, however, want to throw out a new idea that might actually work to a certain degree that would allow non-DRG/Mages to get in on the fun of a wyvern that stores TP and all to be Spirit Linked.
So we all know Strafe sucks, right? Horrible, horrid, wretched merit trait. It has almost no reasons at all to be merited, especially since the breath accuracy doesn't affect healing breath.
Well, the whole focus of Strafe is efficiency and accuracy of elemental breath. But how about instead of boosting the magical accuracy of breath attacks, it instead conserved a percentage of a wyvern's currently stored TP?
For example, each Strafe merit, starting from the first one, would give the wyvern 10-20% of its TP back that was expended from a breath attack. So just for a simple example, if it had 200% TP at the time, it would get back 20-40% TP, depending on what people felt was balanced.
Each merit after the first raises the return TP, or TP conserved, until at a full 5 merits in to Strafe your wyvern is conserving anywhere from 50-100% of the TP it had prior to the breath attack.
Were it me, I'd split the difference to balance this idea and go with 15% per merit. Anyway, just a thought. Strafe needs a reason to be useful, and Dragoons want a way to use Spirit Link to get TP without having to sub mage jobs all the time.