I have seen this spiked device conecting to the strut on the left side of the aircraft on many aerobatic biplanes...here is an example of it on the mighty CEII:



My question is - is this a device used as an attitude reference or is it used for something completely different?

Scooter

Attitude reference. It gives both the vertical and 45 degree reference for manoeuvres such as the cuban eight.

Cool! That airplane is from a aerobatic team, the iron eagles. Great show but, I seen them in videos and those aircraft were at the same airshow as the Blue Angels while they were flying A-4s. They are kinda old team.