In both there is a school in which the students have superpowers and fight each other for some dumb reasons. On top of that those powers often involve materializing weapons. There are many other similarities between those two, but I don't feel like using them as a base for my recommendation.
Akuto Sai enters the Constant Academy for Magick Arts hoping to become a high priest and change the world for the better. But when the school's oracle declares his future profession to be 'Demon Lord', he finds himself feared and hated by the entire student population. Now, instead of making comrades and studying for his exam, Akuto finds himself fighting off monsters, bullies, and well-meaning classmates in various states of undress. If navigating a magical high school as a transfer student wasn't difficult enough, Akuto now has to deal with a cute android ordered to observe him 24-hours a day, the precocious attention of the flying, invisible and naked Keena Soga and the advances of the school's most popular girl. Will he be able to overcome his fate, pass his classes, and mend his friendship with the violent Junko Hattori, or will he succumb to his demonic destiny?
Ichiban Ushiro no Daimaou and Maken-Ki! are very similar harem series (similar setting and characters). Going into details would be pointless, but let me just say this: the first one has better premise and male lead, but the other one manages to introduce some plot at times. This plot, while not great, seems to be better than the plot of Ichiban Ushiro no Daimaou (even if by a hair). In my opinion, both of those manga are below medicore, but if you enjoyed one, you might like the other one as well.
To be excepted into a special school, one must have special powers. Well in the case of Maken-ki and Shade, that's how it went down. Both of our protagonists have an unknown power in which they go to a secret school to learn about. This school also contains other people with amazing powers. Yet, obviously, our main characters have the most awesomest power of all! If your into people with unrivaled supernatural powers and epic power unraveling and the likes, then these mangas are for you. Basically, similar plot.