I found the bent wood arms on the Poang chair too hard and Ikea still does not make padded armrests for the chair.
I bought a package of flexible padded aluminium splint from Amazon.
It is 4.25″ X 36″. The product I got was salmon colored. It had minimal padding but that was ok.
I unrolled, flattened and cut  10″ lengths from either end. I rounded the corners I cut from right angle to gently curved. I made the original factory corners face the front.
I placed the splint on the armrest and gently folded the coverage down along both sides of the armrests.
Done. One might want to use double sided sticker tape to keep the armrest from sliding on the arm.
The splint is padded top and bottom so there is no scratching the chair arm.
While the splint padding is real thin, it is amazing how much more comfortable they make things.
I’m not too crazy about the color. I will be looking out for flexible splint material that more closely matches the cushion cover OR considering how to cover the splint.