system
Given the following post, respond as if you're commenting on Reddit:
human
[Destiny] Does the Light prevent aging as well as violent or accidental death?

During the Red War, Ikora mentions dying over and over, and other Guardians do too. Are they all violent deaths at the hands of enemies, or does the effect of the Light prevent any methods of dying?

It seems like the Guardians should be far wiser and more advanced/numerous if that were the case. For example, could there be Guardians still alive from the Collapse? Can Guardians have children? 

I ask because if Guardians are somehow a race of immortals thanks to the Traveler's influence, it makes a lot more sense that so many alien aggressors would be tripping over each other to get at humanity.
gpt
Yes, the Light does prevent all types of aging, sickness or any other method of dying from permanently killing them.

However, there are several methods of killing a Guardian such as ontological weapons (reality consuming/corrupting weapons) either against  said Guardian or against the Guardians Ghost. Other methods would include killing the Ghost or Guardian in a Darkness Zone or corrupting their bond (like Vex radiolaria consumption or injection).

Yes, their are Guardians still living from the Collapse (or at least in a close period of time to it). Example: Drifter.

As for if Guardians can have children this is still one of the most frequently asked questions in the community. Their is several theories:

1). They can, but if the Guardian (female) where to die the child would not be revived.

2). They don't do that because they would outlive their child.

3). They are sterile.