Root-adjacent and argument structure-modifying morphology has been at the center of a recent debate in morphological theory on the status of verb conjugation classes, "templates", theme vowels and verbalizing morphology in general (Fábregas 2017; Panagiotidis, Spyropoulos & Revithiadou 2017; Kastner 2020; Kastner & Marin 2020; Simonović & Mišmaš 2023; Kovačević, Milosavljević & Simonović 2024 a.m.o). A crucial question is if and how this morphology interacts with root meaning and to what extent it introduces abstract meaning itself (e.g., BECOME, CAUSE, DO). However, these problems are rarely treated from a diachronic point of view (with some exceptions, e.g., Grestenberger 2022, 2023; Calabrese & Petrosino 2023) because 1) there is an insufficient empirical basis for generalizations concerning the diachrony of argument-changing morphology and 2) it is unclear whether changes affecting this morphology should be expected to follow specific patterns, parallel to "cycles" in syntactic change. Based on case studies from Greek (Grestenberger 2022; Marescotti & Grestenberger 2024), NW Germanic (Grestenberger, Werner, Anderson & Sichrovsky 2024) and Latin, I will address this empirical gap and argue that the diachrony of denominal and deadjectival verbs in these languages provides evidence for unidirectional reanalysis paths that give rise to specific types of Aktionsart/v-related morphology. I focus in particular on verb classes that have been described as ambiguous between expressing states and activities and as iteratives/pluractionals in the literature and show how their argument and event structure properties developed diachronically.