[Gorthaur the Cruel]

It seems that Melian is a truly powerfu and wise maia, and maybe even more powerful than the Istari (?). The fact that she was able to fend off a highly empowered (thanks to the Two Trees saps and Varda's wells) Ungoliant, whose darkness strangled all of Valinor's inhabitants (including the valar themselves), is truly impressive... considering it took a host of Balrogs to fend her off of Melkor. Of course, when Ungoliant headed for Doriath, she could have been less powerful due to the Balrogs' earlier contest with her, hence why Melian was able to restrain her? Or perhaps she was still in her full might even when apporaching the Girdle.
This makes me speculate that if the tragedies that transpired in Doriath (resulting in its destruction) did not occur, Melian's Girdle could have indefinitely held off Morgoth's full power (Sauron, Ancalagon, Glaurung, Gothmog and other Balrogs, Trolls, Orcs, and evil men).

In addition, speculate how Melian ranks against other powerful Maia like Uinen, Ilmare, Arien, Sauron, Gandalf, Saruman, and Radaghast in terms of raw power (however you want to define that). Some posters have mentioned that Sauron and Melian are possible equals, but if that were so, he wouldn't have had any reservations about attacking Doriath. Or am I giving Melian too much credit against the might of Angband?