What is one possible analysis for wāw before aṣukku in qumtu wa-aṣukku wajhahu?

Circumstantial Imperfect and Past Verbs: Rules for Wāw al-Ḥāl

• Turning the imperfect into a verbal noun
• Supplying a nominal subject: wa-anā aṣukku
• Treating wāw as case ending
• Making aṣukku a past verb