i have an old friction stem shifter on a bike which is impossible to shift up, but is smooth as butter when coming down.
I figure that since its nice coming down that it isnt the shifter itself or the cabling.

This is true for both the front and rear derailer.

To an extant that's just the way they are, but cable friction may be making it worse.

Old derailleurs had fairly powerful springs and on upshifts your fighting the spring and lever friction plus the opposing forces make the cable bind on curves. In the opposite direction you're working with the spring, and relaxing the cable which now has less friction, so the action is much lighter.

It's the difference between dragging a sack of onions up a hill on pavement, and down on ice.

Before index, some makers "retro-friction" levers which used a ratchet to eliminate the lever friction when up-shifting.

Front or rear?

If it's the front, make sure you have the cable attached properly. It comes up from underneath the bottom bracket and goes over the little tab before going under the washer.

its definitly worst in the front
nice the problem isn't gone but that helped.

ive never noticed my friction derailers being that hard to shift did the amount of force needed decrease over time (pre rachet)

Friction shifters did get somewhat lighter over the years, as improvements to cables made lighter return springs practical. But I think the biggest difference is in expectations. Today's stuff is so light action that the older stuff feels way harder by comparisson.

I think back to the early days of mtn bikes using 6 speed thumb shifters. The action was so stiff, it wasn't that rare for folks to sprain their thumbs trying to downshift. The difference in feel of my current road bike and the Campy barcons on my '67 vintage Frejus is like the difference between my Miata, and some old truck without synchro. I road that bike for tens of thousands of miles, maybe that's why I have a strong grip.