[LoweGear]

Here's my rough take on the differences between the three, based on Wiki info and my own inferences:

Storage Device:
- Only two modes (storage and active)
- No sentient AI, only voice interface

Intelligent Device:
-Three or more modes
-Sentient AI

Both would be Stave-type weapons designed primarily for spellcasting.

Armed Devices:
- Typically built as weapons, used mostly for direct combat as opposed to spellcasting
- typically equipped with cartridge system

Note these are rough definitions, since there's much variety (IIRC KlarWind is classified as an Armed Device despite not fulfilling the above parameters.) I have noticed a peculiar pattern though:

-Armed devices tend to have dormant forms reflecting their true form, i.e. Graf Eisen looks like a hammer and Klarwind still looks like a ring, whereas Intelligent and Storage devices have vastly different shapes, i.e. Raging Heart's a sphere and Durandal's a card.

Again though, this definition is muddled by Reinforce, which is classified as an intelligent device ^^;;

Examples of Hybrids:

Raging Heart Excelion and Bardiche Assault: Spellcasting type intelligent devices equipped with cartridge system, not to mention Bardiche is quite effective at melee combat.

Judging from the loadout of Subaru and the others, we'll be seeing more classification defying devices in the future.