I agree. I can only comment accurately on your thoughts if I see them spelled out. Just posting one comment for each line or stanza can prove really helpful, even if one has no finished guess.
The riddle
No arms I provide, no rest
I'm an option in between
I will put you to a test
in favour of the green
But I'll help you too, don't fret!
A heaven's grant might be of use
Aggregate power you will get
You haven't got much to lose!
So come on, warrior, heed the call!
Though you by coming here
before death's peace build thrice a wall
there is no need to fear.
Wrong answers
Battle Arena
Any of the WEAPONs
The Weaponsmith near Gongaga
Ancient Forest
Sunken Gelnika
(The cave of) The Sleeping Man
The Position Marker (pointing hand)
Green Beret
The Pagoda in Wutai
The person in charge of the Fort Condor battles
Titan materia/summon
Aeris' "hairbeadthing"
Excavation Site
Gold Saucer
Hints
The answer is a location which is optional to visit.
Only one of the lines is purely metaphorical.
"A heaven's grant" is very literal.