Its spell not an item, like rogue poison for example …
It will always cast on MH first then on OH weapon, you could use /castsequence and put WF/FT into it and reset timer, optionally command cancel your weapon enchants …
Or /cast [mod:shift] modifier that allows you to use more imbues in one macro, if you use modifier …
Casting two imbues with single button is the best thing we can do …