If we had a verb for “be alarmed”, you could say, {yI-[be alarmed]Qo’}, but the verb is {ghum} — “alarm, sound an alarm”. In a Statement, we could build “be alarmed” out of {glumlu’}, but when you put the {yI-} on it, the subject is expected to be the First Person.
Or you could say {yay'} "be shocked, dumbfounded" or {bIt} "be nervous, uneasy". The English "be alarmed" doesn't really have anything to do with alarms.
{yI-} is *not* a First Person prefix, but I will assume you know it's Second Person subject and just misspoke.
Well, the statement “I am alarmed,” would be {vIghumlu’} or “-indefinite subject- alarms me."
Does the imperative prefix do the same {-lu’} trick pointing to the object instead of the subject? Is {yIghumlu’} valid for “Be alarmed!”?
I'm going to have to go with an unequivocal "No". The indefinite subject suffix doesn't "point" the meaning of a word to anything that the word doesn't normally point to. It *always* means the subject is indefinite. That is completely incompatible with imperatives, which *always* have a second-person subject.
-- ghunchu'wI'