Guild Wars 2

So im getting my ascended gear piece by piece, but i need to know the correct infusions.
Its a zerk guardian and i was looking at this site: http://metabattle.com/wiki/Build:Guardian_-_GS_Sword/Focus/Torch

It suggests mighty infusions for all trinkets, but seeing they are unique and you can only have one “Ring of read death” (where it would be fine) the “Crystalline Band” has a defensive infusion. From what i understand i would have to use one “Versatile Mighty Infusion” for this one instead or have one of the “Ring of read death (infused)” to be able to get the “Power” perks from both rings. I also dont want to make an infusion and equip it only to have to destroy it upon infusing the ring unless this is a common thing to do.
What would be the best way to go about this?
Thanks
Regards Backer

You are correct on which infusions to use.

Wait until after infusing to apply them, or they will be lost.