In a poem with a strict rhyming structure, how are words with softer, less definite syllables considered? For example 'average' =2 or 3? Can it be either?
Yes it can, but it totally depends on what iambs you're throwing down and how you want the suggested word to fit.
If your metric pattern is already set and strong, the reader will automatically choose the emphasis and syllables that most closely fit. Of course, the more often you rely on that in your poem, the weaker the rhythm becomes, so you need to reinforce your rhythm with words with unambiguous stresses and syllablization.
Wow, thank you both! So far I've relied on my natural abilities and vague memories of literature class. This pretty much solves my predicament
and don't forget you can also use that tried and true poetic technique of syllabic elision, to aid the meter, writing it as "av'rage"...
Thanks to you also. I already considered this, but I haven't known its name which I guess is kinda useful when referring to it