Apart from the safety advice given, if there's no data plate on the fan, you won't know what the Wattage rating is. Don't therefore be tempted to power it from one of the 100 Watt US/UK adaptors, which in any event are intended for intermittent use. Despite the instructions making that clear, there are lots of adverse reviews from idiots who complain that 'they powered an oven or a hair dryer from it and it burnt out right away'. (Why would it not do?).
https://www.amazon.co.uk/Step-Down-C...gateway&sr=8-6
Modern fans of a similar size to yours are typically rated at under 50 Watts, but you've no way of knowing unless it was powered from a metered 100V power supply to see what current it draws.
If it was put back into safe working order, something like this, rated at 500 Watts, which has a proper transformer, would probably suffice, but would no doubt cost more than the fan is worth:
https://www.amazon.co.uk/Bronson-Tra...ateway&sr=8-14
Given the obvious mechanical work needed (brazing/hard soldering the wire fan guard), the insulation needs careful visual examination and checking with an insulation tester ('Megger'), and rewiring, if you don't have the competence and experience to do that, in my view the fan is beyond economic repair and should be considered a decorative curio of a bygone age.
Probably not the answer you're looking for, but good luck with it anyway, whatever you decide to do with it.