I am not familiar with 40 mm scene, but some of the 28 mm sets out there are sufficiently "heroically proportioned" that they migh pass as weapons for more realistically proportioned 40 mm models.
Especially I would consider Fireforge Games, well known for their rather well proportioned armaments - they have a small range of separate plastic weapon packs, including spears of various lengths. I purchased a few packs last year through Caliver Books.