This sort of thing happens when you have an individual loot for each of the eight (six for the four body-pieces) classes and you're only getting 2 drops per. Some of the equips are consolidated based on roles requiring the same stats, such as healers, casters and tank (Healing, Casting and Fending pieces), but not the case between DRG and MNK (Maiming and Striking Pieces) and BRD being the only one utilizing dexterity (Aiming). That inconsistency is something I never really understood since afaik MNK and DRG desire the same stats more or less... And I'm further confused by the fact they have jewelries appropriate for both classes (Slaying).

One thing they could do is work on a token exchange system similar to what WoW did for their first expansion; A boss would drop a token for one of the main body pieces (Head, hands, Legs, Feet) and they would be exchangeable/appraised for the relevant equipment slot for the classes eligible. Example...

Allagan Gloves of the Derp - PLD, MNK, THM
Allagan Gloves of the Cheesemaker - WAR, BRD, SCH
Allagan Gloves of the Winemaker - DRG, SMN, WMN

The Glove tokens can be exchanged for a piece of gear for those classes in each category. It'd allow for more diverse looking gear (WAR and PLD don't share the same armor skin and have their own unique one). It's just an example, it could be further categorized with the introduction of Ninja, (although I wouldn't pair tokens based on roles/stats, otherwise groups would feel obligated to bring a certain class just so loot doesn't get wasted more than it already is)

Accessories would stay the same, if not get rid of the Maiming and Striking pieces on Bracers (unless this is considered a main body piece) and consolidate them into Slayer's. Weapons also stay the way they are since they are technically the best slot upgrades for each class no matter how you slice it.