My friend found this outfit in a box in his basement. What is it/what is it's historical significance?

by JupiterSam
brojangles

Those triangles look like they might be Masonic triple tau symbols. Masons also use six pointed stars as part of the imagery (there is a six pointed star on the outfit) and the number seven (note those tassel things each have seven strands and seven beads or pearls on them).

Sorry I can't do better, but I hope this can help get you on the right track at least.