The photos aren't the best, but, from what is there, as far as authenticity, I see no problems. Condition could be another matter. The blade looks like it might has been seriously abraded to do away with corrosion. But that could be the light, etc., or it could have darkened with age. The fittings on the dagger and scabbard look highly polished, or they could be the plated type. If they are, I would want to know if there is any lifting to the plating and if any has peeled away. As always, insist on a return privilege from the seller. If you have questions after receiving it (assuming you buy it), try to get better photos and post them here for evaluation.