This paper investigated grammaticalization phenomena displayed by six movement verbs of manner that grammaticalized into 10 postpositions, with special emphasis on their morphosyntactic characteristics. These postpositions include non-finite markers in their formal construct and they have morpho-phonological complexity. They were derived from verbs but from a verbhood test by using the honorification marking, they show departure from their verbal status and development into postpositions, which indicates decategorialization, a process invariably associated with grammaticalization. In addition to the inter-categorial differences (e.g. from those of verbs), these forms show different intra-categorial differences along such criteria as accompaniment of particles, orthographic spacing, morphosyntactic transparency, tolerance of adverbial/particle insertion, and phonological loss. All these indicate variable degrees of syntagmatic cohesion, a fact that lends support to the thesis that grammar is inherently fluid and is constantly emerging.