I know this sounds feddy, but bonus if they're improvised, cos that shits awesome.
One of my favourites is the PRIG - an IRA made grenade launcher that used a packet of biscuits to offset and quieten the backblast.
I also made a crossbow that fired nuts and bolts using wood and resistance bands. Not a weapon of war and would never be lethal, but also probably not very legal where I'm from. I just used it to plink cans in the back garden when I was bored. Was actually quite a scarily powerful and accurate device for how crude it was.
the horse-bow combo is the most graceful and until firearms most effective loadout. horses with people who really know what they're doing on top are so elegant, and bowmanship was already very pretty on the ground.
a parthian shot from a speeding horse is something to behold
failing that the halberd is the coolest single weapon in a vacuum