Take a look at Tidus's Water Sword in FFX. It has the appearance of being made out of water, complete with the occasional bubble rippling along the surface of the blade. It also has a slight wave-like structure to the blade. I think that may be what the OP was trying to say, but got lost in the particle mechanics.

I would find such a design to be a welcome addition to FFXIV, as it would allow for a visual representation of what elemental properties a weapon has. Right now, the only difference between a Storm Axe and an Iron War Axe is the name. The actual weapon model is the same for both weapons, despite the fact that the Storm Axe has elemental properties attached to it, whereas the Iron War Axe does not. In fact, if I saw a bunch of Marauders standing around and there was an even mix of Storm Axes and Iron War Axe's, I wouldn't be able to tell which Marauder's had Storm Axe's and which ones had Iron War Axes without examining each and every one of them.

There is no reason not to have a weapon model look like what the weapon's name is suggesting the weapon is. And, as FFX (a game that is 10 years old) proves, it is possible to have weapon models that are aesthetically pleasing while giving a sense of uniqueness.

As far as armor goes... that's a tough one. It would be difficult to apply the same aesthetic to armor without running the risk of coming off as overly chintzy. It could be done... it would just be very difficult. Elemental armors would have to be designed to visually reflect whatever the major element of the armor piece has. Something akin to this:

Water: Utilize shades of blue to add highlights to the piece on it's texture map. Actual piece geometry should suggest flowing waves and/or ripples.

Earth: Utilize shades of brown to add highlights to the piece on it's texture map. Actual piece geometry should suggest a degree of rigidness and uniform lines

Fire: Utilize shades of red to add highlights to the piece on it's texture map. Actual piece geometry should suggest the randomness of form that is often attributed to a flame.

Air: Utilize shades of white to add highlights to the piece on it's texture map. Actual piece geometry should suggest a chaotic structure with a distinct lack of uniformity.

If the above was used as a baseline, it would be possible to create gear that gives a visual representation of each gear piece in a way that is aesthetically pleasing and provides the opportunity to have diversity amongst the different sets of gear (so if the same helm is augmented with fire-based materia, the resulting helm would look different from a helm that has been augmented with water-based materia).

Note that what I am talking about for weapons and armor does not utilize particle systems to create glowing effects. What I am talking about would require creating unique artwork and geometry. As such, it would require a lot of time and work... so it should certainly not take a higher priority over existing TODO tasks.