The verbs vicessati and pacessati in this verse appear to be unique. I take them to be from the Sanskrit ceṣṭ (“move, explore”) rather than ci (“gather”). They can then be read as present tense, which makes better sense of the verse. Sanskrit and Gandhari parallels have a variety of forms, all of which maintain the distinction between the vi and pa prefixes.
I take vicessati in the sense “stir, agitate”, with reference to such passages as AN 7.69:15.1, where the noble one inspires the gods. The commentary, rather, suggests the sense “explore, investigate”. A variant reading vijessati yields the sense “shall conquer”.