*-(i)janą^²

From a pre-Germanic thematic renewal of the older Proto-Indo-European athematic stative suffix *-éh₁-. In PIE, this suffix formed stative presents and appears to have been accented, non-ablauting, and athematic, as reflected by Latin second-conjugation statives such as rubēre < *h₁rudh-éh₁- and tacēre < post-PIE *tak-éh₁- (Ringe 2017: 157, 203–206). In Proto-Germanic, however, the inherited athematic stative was replaced by a new thematic suffix complex *‑ə‑yé/ó- (Bennett 1962), apparently from *-h₁-yé/ó-. According to Ringe, this arose when passive/resultative participles in *-h₁-tó- were created beside the old stative presents; the suffix complex developed regularly to *-ə-tó-, and new presents in *-ə-yé/ó- were then back-formed from those participles (Ringe 2017: 157).

In PGmc this yielded the class 3 weak-verb alternation *-ai- ~ *-ja-, with *-ai- continuing the e-grade-like alternant and *-ja- continuing the zero-grade/thematic alternant. This alternation is preserved most clearly in relics such as Old Norsesegja and þegja, and is presupposed by northern West Germanic class 3 forms; Gothic and the majority Old Norse type later generalized or remodeled parts of the paradigm, while Old High German generalized -ē- < *-ai- (Fulk 2018: 308–13; Ringe 2017: 158, 286–89). Ringe treats Weak class 3 as historically connected with PIE *ē < *-eh₁-, with or without a thematicizing suffix, and notes that a major PIE use was deadjectival statives meaning ‘have the quality of the adjective’, alongside deverbal duratives and some Gothic factitives.