Quote Originally Posted by Kennar View Post
Any piece of gear that is bound to you can travel through the aether with you
It may also be a question of how much "energy" is needed to accomplish the journey.

According to the lore book, magicks are used to reduce the corporeal body and will to just aether, with the will keeping it together, and passing through the lifestream to another place where the boundary is weaker (on Hydaelyn, that's the location of Aetherytes) at which point they pass back into the corporeal realm and reform.
It's quite possible that the amount of magick needed to break down inanimate objects grows at such a rate that beyond a certain point (say, the weapon, clothing, and a certain amount of carried items - lore wise I don't think we actually carry quite as much as we can gameplay wise) it's simply not feasible to do so - either it would take too much magick, the will of the host can't keep it all together, or both.

Also, in terms of can it change something like food? I think it's possible, though I doubt it would be so drastic as ending up with a different type of food. That being said, it would take spending longer in the lifestream than you normally do when using the aetherytes, as those act as beacons and you spend so little time in the lifestream that everything that goes with you arrives in the same form.

Y'shtola returned without her natural sight and instead has to sense the aether around her to see, and Thancred was spit out without the ability to tap into aether at all, so teleportation can make changes to the aether that is involved in it...but only if that teleportation doesn't involve aetherytes at all, or perhaps if something were to happen to the aetherytes at the same time you entered.