How do I set the size of an actor object in a 3rd person RPG?

I have an actor object that is a sword. I want to set it to exactly 90 cm or 90 uu and have it scale the other dimensions. How do I set the length exactly to 90uu? I do not like eyeballing it until it feels right, I would like it to be exact.

I am using a static mesh for the weapon