In general, such an easy word as عابدين doed not need any fatha for the exact reading, and I do not remember [but no more] any remarkable usage of fatha in the MS. The Christian Arabic Mss often use only damma.
Yes I agree but in the MS we find a few uses of fatha - and more surprising, almost always in "useless" situation (before an alif)
I wondered several times about this.
126r, l. 9 مَا
155v l. 23 رِسَاله + l. 25 المُدعَى
156r l. 25: صَادق
156v l. 18 وَاحدًا
etc
Yes, these are real fathas in the form of stretched lines, used to fill the gaps by aesthetic reasons. But that of below فحينيذ or above عابدين looks more like dot, quite similar to that two lines below in يعرفكم .
