Cannot roll Need on class-appropriate gear

Time: First occurred on 8-12-2014, 11:44pm PST (GMT-8)
Frequency: Nearly every time treasure coffers are opened.
World name: Aether - Cactuar
Character name: Nikolas Kaulitz
NPC name: N/A
Monster name: N/A
Class/Level: Gladiator 15-25
Party or solo: Party
In-game time: Unknown
Area and coordinates: First occurred in Sastasha, at (12,10).
Steps:
1. Defeated a boss that dropped a treasure coffer, or otherwise encountered a treasure coffer (this happened on multiple occasions, with varying circumstances).
2. Opened the treasure coffer and it contained GLA/PLD gear.
3. Attempted to roll Need, but the game would not allow me.

Connection Specs
- Type of internet connection/provider: Comcast Cable via ethernet cord (38.4Mb/s down, 10.3Mb/s up)
- Modem maker/model number: Unknown, likely Comcast proprietary.

PC Specs
-=-=-=-=- System Information -=-=-=-=-
Toshiba Satelite E305-1995 (produced in 2011)
Intel i5 @4x 2.33GHz
Intel HD Graphics 3000M (Sandy Bridge) @129.6GFLOPS, 1.35GHz, 2.048GB VRAM.
6GB Main RAM
Inbuilt screen is broken, so the machine is hooked up to a secondary monitor
1280x1024, 75Hz, 32-bit colour. (Secondary monitor)

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Laptop Model Name: Toshiba Satelite
Laptop Model Number: E305-1995

Gamepad Manufacturer: N/A
Gamepad Model Name: N/A
Gamepad Part Number: N/A

Browser Information
- Name and version of the browser currently in-use: Google Chrome 36.0.1985.143 m
- Internet Explorer Version: IE10 installed, all IE features disabled.

Additional
Screenshot of the bug: http://i.imgur.com/2kPpInE.jpg

The plundered haubergeon is actually lancer gear that just happens that mrd/pld can equip, only lnc/drg can need on it. The plundered cuirass is the actual tank drop that you can need on in the dungeons.

Yep. The item has more Def than Mdef, so it is not tank gear, it is LNC/DRG gear.

Tank gear will have even Def and Mdef, while LNC/DRG will have about half as much Mdef as it has Def.

Weather it's actually designed for tanking isn't of particular relevance. As I understand it, you can roll Need on anything you can equip, and it's equipable to Gladiator. The same issue also happened with other gear pieces in other dungeons, though I didn't think to record those instances. I think at least a few of them were specifically GLA/PLD gear, but that's just my memory speaking.

As you understand it there are also exeptions and this is one of them. You are able to lot pieces that benefits the most to your class. Is the same with the accesories, they are all classes but only the class that gain the most can need them.