I'm trying to do the following macro:

/cast [equipped:dagger,stealth] ambush
/cast [stealth] garrote
/cast backstab

Problem is if I have a dagger in the off hand slot, it considers that a dagger equipped for macro purposes and makes ambush the spell of choice though ambush only works if a dagger is the main hand. So is there any way to make this equipment check apply only to the main hand?

Thanks.