Edging a wonky glass wall

[StumpedCanary]

I seem to have been the target of not entirely professional workmanship again... I had a wall built in the kitchen, half concrete blocks (I think) and the upper half of glass blocks.
However the wall tappers very slightly towards the bottom and the uppermost glass block is slightly offline.
I've found an aluminium bar which can be fitted (upwards) on the end of this wall - my question is, can I add this without it looking bad or should the wall be corrected first? (Don't want to buy the bar & struggle home with it if it wont work...).
Advice gratefully received & thanks in advance.