Force - Between Maul and Dooku but closer to Dooku.
Sabers - In terms of pure skill, maybe Ventress. Counting both skill and augmentation, most likely around Kenobi if slightly lower.
Overall combatant - Around Obi Wan but with some tweaks. I'd say the power advantage is greater than the saber deficiency, so I have him slightly above Obi Wan.
Hardly. Almost everyone has him around the same general area of "better than Maul, worse than Vader," a few no-longer-vocal outliers aside.
IMO, Bane's greatest strength (as opposed to other fighters of similar class, like Zannah) is that he's just good across the board. He's very strong and pretty fast, his fighting style is overwhelming but still riddled with subtle kinks, he's strong with the Force and can utilize a fair array of dark side powers, and he's both highly intelligent and resilient. He's probably most competitive with fighters like Obi-Wan Kenobi, Count Dooku, or Darth Malgus, although I wouldn't personally favor him over any of those three without his Orbalisk Armor.
__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk
In terms of lightsaber combat, I would generally rate him as somewhere around Plo Koon or Savage's level, maybe Mara Jade's level, give or take. Can't really be sure to tell how close exactly he would be, and honestly, it's not like lightsaber combat is a mathematical variable you can provide numbers with.
In terms of Force power, quite better. Above Darth Maul, below Naga Sadow or Karness Muur, above the lesser of the famous Ancient Sith, like Ludo Kressh or Sorzus Syn.
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They are angry because they have been forced to recognize that their hour has arrived; that the time has come to surrender power to Shimrra and the new order."