My preference, would be a cape combining system.

Let's say you have two augmented capes of the same type. You trade one to the NPC to be used as the base. Then the second to be used as the material. The base would maintain is full current augments.

In the case that both capes had the same type of augment, the potency would be increased by a small increment for each matching aug. +1 for things with low caps like str+. Maybe 2~ for stuff that caps at 20 like indi effect duration.

In the case that the material has an augment the base doesn't, that augment would be added to the base at a reduced potency. Probably half or less.

This method would retain a fair bit of the RNG, since you have to farm enough capes of the proper augs to build your cape up. But it removes the total frustration of having to try to roll that 0.0001% chance of the right cape with perfect augs. This way you can build up you cape slowly over time. Benefiting slightly every time you manage to get a cape for your jobs.

You might think this would make ppl finished too fast, but I don't. The RNG is still very much there... After god knows how many skirmish MB runs, I've still NEVER seen a Phalanx+ augment on PLD cape at all. Much less a +5. So even if this system had been implemented from the start, I'd still be working on it. I'd just be a hell of a lot less pissed off. And have better capes for my other jobs. -.-;

The down side, is that this is a bit more complicated to implement than a simple trade in for a reroll system. But hey, that doesn't matter. SE isn't gonna implement either of these anyway, so the difficulty for the devs is a non-issue. lol