What praises do Hero and Ursula use on Benedick, and how do they make him seem pitiful?

I think you are referring to the conversation between Hero and Ursula in act 3, scene 1, of the play, when the two women discuss Benedick's feelings for Beatrice in Leonato's garden.
Hero declares that when Beatrice arrives, "our talk must only be of Benedick," and they must "praise him more than ever man did merit." At this juncture, Beatrice enters, and Hero and Ursula move closer to her so that she will be able to hear all the "false sweet bait" they intend to offer her.
Ursula declares that Benedick "deserve[s] as full as fortunate a bed / As ever Beatrice shall couch upon," and Hero agrees that he deserves "as much as may be yielded to a man." However, Hero also says that Beatrice "cannot love." Ursula agrees with this and says that she is glad Beatrice does not know of Benedick's feelings for fear that she might "make sport at it." Naturally, this makes Benedick appear pitiful: the women are suggesting that they feel protective of him because of his feelings, and they are suggesting that they do not wish Benedick's feelings to be hurt by the "self-endeared" Beatrice.
The two discuss how Beatrice tends to criticize even seemingly perfect men, and they determine that Benedick should be allowed to "consume away in sighs, waste inwardly," as this would still be better than for him to "die with mocks." Hero then determines that she shall go to Benedick and "counsel him to fight against his passion." The two women agree that Benedick is a "rare" gentleman; indeed, he is "the only man of Italy," and a man who "for shape, for bearing, argument and valor" is peerless. He also has "an excellent good name." Altogether, the two create a picture of Benedick as a wonderful man, much wronged by Beatrice, who is forced to conceal a great passion for her out of fear of being unfairly mocked.
Their machinations ultimately succeed; Beatrice is moved by the "bait" and declares that she will "requite" Benedick if he does indeed still love her.