The rust erasers are abrasive (silicon carbide), and will leave a somewhat 'satin' finish behind (fine scratches). If you don't want to otherwise alter the patina/finish on the blade, I'd avoid using those.
Some WD-40 applied and allowed to soak for a little bit, would loosen up much of that rust. Scrubbing it with a toothbrush or a brass brush could also help in conjunction with the WD-40. Mineral oil can also be used instead of the WD-40. Sometimes very fine steel wool (#0000) works well with WD-40, though it needs to be used lightly. On newer and more abrasion-resistant steels, it'd be fine. On older blades, it sometimes may or may not scratch a little bit. If used lightly, with some lube/oil/WD-40, it'll likely be fine, but you might test a small spot first, just to be sure.
A product called Bar Keepers Friend is about the most effective rust remover, but it uses oxalic acid. If used with water, and not allowed to remain in contact with the steel for more than ~30 seconds or so, it works very well (apply & rub specific spots with a Q-tip, with the powder mixed to a paste with water). The acid will do virtually all the work, so very little scrubbing is needed. Light surface rust will disappear in seconds. It may also remove some patina in the process, but that can come back in time. Just make sure to thoroughly rinse the blade in running water afterwards, and dry/lube/protect the blade as you ordinarily would.
David