If you're looking for anime similar to Zero no Tsukaima: Princess no Rondo, you might like these titles. All recommendations are made by Anime-Planet users like you!
Cecily Cambell just wants to be a Knight and protect her home like her father and grandfather before her. There's just one problem: she’s incompetent! During a fight with a crazed swordsman, Cecily’s cherished blade breaks; and just as she’s about to be cut down, a man named Luke comes to her rescue wielding a katana - a blade unlike any Cecily has seen before. Together they must ensure that the Demon Sword Aria doesn’t fall into the wrong hands, and Cecily alone must prove herself worthy of her very own katana.
Zero no Tsukaima (or Zero's familiar) and The Sacred Blacksmith remind me of each other, mostly because they both inherently put most of their time into combat or a little of romance between characters present. Zero is much longer and more drama/romance driven than The Sacred Blacksmith (it is also more wacky) but they both juggle those two concepts constantly.