Sometimes I get legendary items with 3 defense. Why are them for? Does those items have anything special when you upgrade them? Can I destroy (recycle) them?
Compared to the rest 250+ defense items, the first ones worth nothing. It is strange to me that this happens, so maybe it have a reason.
The only source 3 Light level gear is the gear you get from Spectral packages. As of the release of Rise of Iron, the only way to obtain a Spectral package is by completing the Level 41 Prison of Elders. This can be done once per week per account.
Prior to the release of Rise of Iron, there were three ways to get Spectral packages for free:
You could also buy Spectral packages for Silver prior to Rise of Iron. Silver can be bought from Xbox Live / PSN for real money.
The reason that they only provide 3 Light is because they can be bought for real world money. In order for them to be usable, you will need to infuse them with gear you got from playing the game. This is to prevent "pay to win".
The 3 Defense items are generally considered to be cosmetic in function, and are typically much easier and less random to obtain than normal legendary gear.
As of one of the last updates all Infusions take place on a 1 to 1 scale. As such, if you've got a spare 250 Light Legendary you can infuse the 3 Defense one up to 250 immediately.
