How much wasabi? Try it by taste? I'm making this tonight - sure it'll be sumptuous. Thank you for sharing your recipe! Much Aloha!

How much you will want to use will depend on how hot your wasabi mayo is, and your personal preference. Some commercial products have less heat and taste than others, and even what you make at home will vary depending on whether you use a powdered, paste, or grated form of it. I would just taste what you plan to use, and adjust from there. If you wanted to experience more sting, you might consider serving the swordfish with a dollop of the wasabi mayonnaise on top, much in the way steaks are topped with an herb butter.