The affixes ṭhañ and ṭhak come in the sense of 'this is whose weapon' after the word paraśvadha,
This affix ठक् is added by च, the difference being in accent. Thus पारश्वधिकः or पारश्वधिकः ॥ परश्वध means 'an axe'.,
परश्वधाट् ठञ् च
Adhyāya 4 · Pāda 4 · Rule 58