Shana would still own all, since she can summon Alastor and actually survive doing it... But without it, i think it would be a draw... both have wings and extreme reflexes. No point in carrying a longer sword if cant land a strike...
Because it's not so much a "summon" as it is calling her world setting's equivalent to god into this world. She dosn't just summon him and step back either, since their souls are effectively linked, Shana *becomes* Alastor. Remember when Tellah tries to use Meteo to kill Golbez? or when Fusoya and Golbez double cast it against Zeromus? Sepheroth's casting would be like that. Nothing.
