how about a artifact that reduces your current age by half and then prevents you from aging any further. I know everyone has like eternal life and age is not a factor. This is just purely for rp though.

A fanciful concept, but not something I see people wishing to pay money for, as your children qould quickly become older than you are, and to be honest, not worth spending money on

See: Penumbra.

yeah I don't think anyone would pay for it, but I think the concept would be interesting, maybe made into a quest of sorts but then it might be to easy to aquire

It's a Night coven skill. Anyone who participates in a Penumbra ritual has their age set to 18.

Ask for I.D.'s. Who knows how many Penumbras have suddenly aged two years.

'Cept the English ones. Le-gal.

And the French Canadians.

But yes, Penumbra is exactly what you're asking for.