The pipe’s not as bad as you might think; i’ve used it for 10-15 minutes at a time without problem. You’re spot on as to the process for making the maces. I prefer the one with more cuts – i was worried the the slimmer flanges might bend, but once welded the curvature gives them enough strength.
I like the idea of sharpening; you could do a 90 degree twist sharpen and weld which would give each one decent support.
Edited to add: the torq you can get by holding the base of the glaive/halbard to swing is insane; straight through 2 inch saplings. Gives me a real appreciation for polearms with a blade on the end – quite different to just using my bo-staff