Concerned with bachelor, Armstrong considering all factors (2,7)
I believe the answer is:
on balance
'armstrong considering all factors' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'concerned with bachelor' is the wordplay.
'concerned with' becomes 'on' (I've seen this in other clues).
'bachelor' becomes 'balance' (I can't explain this - if you can you should believe this answer much more).
'on'+'balance'='ON BALANCE'
Can you help me to learn more?
(Other definitions for on balance that I've seen before include "Taking everything into consideration - use scales" , "Considering everything there is to know" , "Having taken everything into consideration" , "Taking everything into consideration - using scales?" , "Be on canal to weigh up everything" .)