To me, it is clear that there is no direct link between the Sanskrit instrumental -ena and Modern Marathi forms like देवाने.  Old Marathi has देवें, and at some point -ने in singular and -नी in plural emerge.  It is unlikely that Marathi would be reverting directly to Sanskrit in this late phase.  The old Marathi inscription has चामुंडरायें करवियले, where Modern Marathi would have चामुंडरायाने करविले.  G. V. Tulpule in his यादवकालीन मराठी भाषा provides many forms that have a similar ending, i.e गंगराजें, दंडनाकें, सावंतें etc. and the plural forms like गुरवीं, पंडितीँ, म्हाइंभटीं etc.  The endings that appear in Modern Marathi are not there in the Marathi of the Yadava period.  But ज्ञानेश्वरी has a few forms like तेणे and जेणे and देवाचेनि, indicating that the endings ने/नि do exist at least marginally in Old Marathi.  Some have connected this to the influence of Kannada in the neighborhood.  However, the endings -ने/नी are to be seen in the Marathi of the Peshwa period and then they continue into Modern Marathi.