Both and neither at the same time.
There are huge consistencies when we truly boil down strengths and weaknesses.
Many times they are opposites and if we focus on one, the other one gets better. Meaning they both get better.
I learned today, my biggest weakness is that I don’t know anything naturally. Most things I have learned in my life are by conscious choice.
My greatest strength happens to be that I can focus and learn nearly anything I set my mind to.
What happens when I build my strength? It gets stronger. Why is my strength so big? Because my weakness exists. If I didn’t have that weakness, my strength would be so strong.
They help each other, and we can apply this in our daily lives!
Personally, I’d say to focus on making your strength stronger, as your weakness will improve in one way or another because of it.