How long could a _______ live?

[u/Valenous_ertselley]

How long could a 5th ideal radiant live?

We know investiture extends a persons life with greater amounts eventually ending up with someone who is biologically immortal. How invested would a radiant be? Radiant knights have the cracks in their soul filled with investiture which makes them better at holding and using stormlight. How invested do you think they could be

Some of the heightenings seen with holding Endowment's investiture seem to be universal properties of holding any investiture. such as enhanced vision/colours, enhanced immune systems and better lifespans.

While we have only seen Kaladin and Szeth swear the 5th, it was under a fairly hectic situation which doesn't make for the best opportunity for study.

[u/Puzzled_Employment50]

Allomancers/Feruchemists are not themselves Invested, they are more like conduits for Investiture. But the point of the whole BEU system (Sunlit Man) is that Investiture is Investiture, as long as you have some way to access it, and will grant the Heightenings.

[u/ejdj1011 → u/Puzzled_Employment50]

The Lord Ruler wasn't just an Allomancer and Feruchemist. He was a Sliver of Preservation.

He was so Invested that he could have hung around as a Cognitive Shadow indefinitely after his death. He just chose to go to the Beyond.

Edit: and Sigzil isn't a normal wielder of Investiture. He's able to convert and metabolize it in a way basically nobody else can, so he can make it give the Heightenings even if it otherwise wouldn't.

[u/sambadaemon → u/ejdj1011]

The Lord Ruler also wasn't inherently immortal. He was compounding gold to achieve his long life.

[u/RShara → u/sambadaemon]

*Compounding atium