There are currently two types of Tomes in Final Fantasy 14: A Realm Reborn. You’ve got Mythology (Myth) Tomes which purchase level 90 gear and accessories, required to obtain Zodiac weapons. Then you’ve got Soldiery Tomes which purchase level 100 gear, accessories and weapons. Myth Tomes have no weekly cap. There’s an overall cap of 2,000, but as long as you keep spending Tomes, you can continue to acquire them with no restrictions. Soldiery Tomes are capped at only 450 per week, resetting every Tuesday morning (in the US).
While it may seem as though you can spend your Myth Tomes however you choose, there’s a recommended order of use to ensure you have the best gear for your character at all times. In addition, with how limited Soldiery Tomes are, and their many uses, it’s best to have a specific purchasing path to ensure you do not waste these valuable Tomes.
When it comes to armor, your first priority should be body armor, followed by legs, then generally hands; head and feet armor are close in stats and vary in importance based on your job and existing armor. The waist armor and accessories generally follow. While this is all fairly straightforward, if you have one job you’re obtaining gear for, you still have to determine when and how you spend your Tomes. Do you get the Weathered main armor first while obtaining Myth accessories? Do you alternate between the two? There are quite a few choices. The situation becomes even more troublesome when you gear up multiple jobs.
If you have an infinite amount of time to play the game, this isn’t really a problem. Simply pick up your Myth items in order of importance (body, legs, hands, etc.), then swap out your Myth gear with Weathered armor as you obtain the necessary Soldiery Tomes. Unfortunately, most people won’t have an infinite amount of time to play, and they likely won’t gain many Myth Tomes by playing more once they’ve capped Soldiery Tomes for the week.
As a tank, defense is extremely important. Because of this, you should focus on your armor first, which means getting the Weathered body and Myth legs first and foremost. It will take two weeks to obtain a Weathered body, and two more weeks if you want Weathered legs as well. By getting the Myth legs, you get level 90 leg gear quickly instead of waiting a month for the Weathered legs. Once you have these two items, pick your next Weathered piece (hands, feet or head), then purchase Myth gear for every other armor slot except the one you selected for Weathered gear. Follow this with the Myth accessories, and one Weathered piece a week until you have replaced your Myth gear with Weathered gear.
If you’re playing as a damage dealer (DPS) or healer, defense isn’t as important as damage output or heal potency. For this reason you want to start off with the same body and legs priority, but then go for the Myth accessories before the main armor. You can purchase those much faster than you can the main armor, and in the meantime you can supplement your lack of Myth and Weathered armor with gear from the Crystal Tower (which also rewards 100 Myth and 10 Soldiery Tomes).
Now, if you’re a mathematician and want to be extremely precise about upgrading your gear, you should make a chart. Compare the stats of your current gear with the stats of Myth and Weathered gear. Once you have the complete stat comparison, purchase gear in the order in which you will get the largest stat boost for your primary stats. This would be vitality for tanks, strength for Monks and Dragoons, dexterity for Bards, intelligence for Black Mages and Summoners and mind for healers. As you upgrade your gear, continue to update your chart so you know what piece to buy next. Keep in mind that you can buy two accessories for the price of one body or leg piece.