I see the promotion but im not sure if its working

where do i see if this mod is working? i don't notice a difference in combat strength.

You're right, although it wasn't meant to function as a brain-dead boon, but as a wonder that requires some strategy. Keeping your oldest units alive will grant you the ability of building up a strong 'elite' core. I didn't want a flat-boost that applied to everything and everyone, reflecting the exclusivity of using the Skyforge (to benefit the Companions only).

Currently not modding anyway. Thanks for the feedback, though!

Personally, I like the idea of the wonder but the effect has a weird effect of encouraging hoarding soldiers and being useless for new ones. Skyforge steel seems like the kind of thing that would make even a new soldier perform better in battle, but here its practically dead on arrival unless you build up right before a new technology.

I think the exact value still needs some finetuning, although I would need some actual feedback. This wonder could be very strong, but it depends on your playstyle, victory type you're pursuing and such. If you're a warmonger, you'll probably lose some or all of your older units along the way (although it probably depends on the difficulty). If you're mostly peaceful, you'll probably have a strong defensive army in the future era. Maybe 5% or 7% is better, but 5% barely matters in the first couple of ages.

I love it thematically, but it seems very strong, especially if playing Zulu.

Have you heard of the companions? they have a base in Whiterun.