I'm far from an expert on Maori culture but central to their worldview is the concept of "mana", which is essentially spirit. Your own mana and that of your ancestors was incredibly important, and that mana could be imbued in items.

Exchanging gifts of mana was a big cultural/social tradition. It seems reasonable that a valuable and distinctive item like a feather cloack would have had a lot of significance and tradition surrounding it. That doesn't mean there were cloak specific prayers but I doubt the ceremonies were completely baseless.

When they talk about the ceremonies and personify the cape (which does sound a bit odd the way it's written in the article) I'm pretty sure it's referring to the spirit of the previous owners, and I'm not surprised that Maori with a traditional sense of spirituality would find a lot of religous importance in that.