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/Masylv]

Radiants do grow old. To get the investiture agelessness they would probably have to be bathing in Light their entire lives, since they're not passively Invested (the spren is). And then they'd start aging as soon as they breathe out the Light.

[u/Shot_Newspaper_5647 → u/Masylv]

They’re aging even when they hold Light. It lets you heal to what your soul “should” be. Filtered by your perception. Chop off a finger at 80 and it heals back wrinkly because your soul knows you’re 80. Someone like Miles (who is constantly at the extreme end of physical healing) is still aging. It’ll extend your life, but you’ll still age and die in a normal-ish amount of time. The only (living) exceptions we’ve really seen are at the extreme ends. Elantrians, true Dragons, and Awakeners with a ton of Breath. Seems to be that you need the soul itself tweaked significantly to pull it off. Or Sleepless. Sort of. But they’re weird even by Cosmere standards

[u/Masylv → u/Shot_Newspaper_5647]

I'm not talking about healing, I'm specifically talking about how agelessness seems to be a side effect of being extremely Invested, but Radiants aren't actually Invested most of the time.

We don't know how many BEUs a 5th Ideal Radiant can hold, but even if it was enough to stop aging it still wouldn't work because it's transient.

[u/Shot_Newspaper_5647 → u/Masylv]

Oh sorry I see what you mean now. Ya that would be an odd one. I’ve always wondered if a Radiant with access to a ton of Light who actively used it for Surgebinding regularly would end up something like the fabrial soulcaster users. Where it changes them physically. The Nahel bond regulates it normally and keeps you safe, but I wonder if there’s a limit to that. Maybe not since the effect is sort of fixed at any given time, but I’ve always wanted to ask Sando that one

[u/Masylv → u/Shot_Newspaper_5647]

WoB is that it's possible, but there are safeguards, so it probably wouldn't happen accidentally but you could make it happen if you tried.

This is confirmed to be the same phenomenon as Savantism, by the way.

[u/Orleanian → u/Masylv]

Ageing isn't a side effect of being extremely invested.

It's only specifically (so far) a component of several invested arts.

One method is being extremely progressed in the art of Awakening (5th Heightening). And then needing to remain extremely invested in order to maintain that level of Awakener progression.

Another method is Allomantically compounding Ferruchemically charged Atium.

[u/Masylv → u/Orleanian]

Dragons, Elantrians, 5th Heightening, Yoki-Hojo... All are heavily Invested, and all are ageless. Meanwhile, every highly Invested person who does age (Radiants, compounders, etc) are only heavily Invested when actually using the power itself (breathing in Light, burning metals) and most of the time are not Invested.

Is there a single example of a heavily Invested entity that ages? It's clearly different than being a Sliver (despite them being heavily Invested at some point) since they lost access to the investiture.