Green Crystal is a 1991 game by Compile. As best as I can tell, it came out in a compilation disk called Disc Station Magazine #32. It’s basically a Might and Magic like game on the MSX 2.
The fighting system is fairly basic. Enemies don’t have a lot of animation, and the game has a typical level of grind for this kind of game. There are handy icons showing you if you have weapons equipped. As best I can tell, the fights are purely attacks from the hero versus the enemy’s attacks. There doesn’t seem to be any magic unless if there are magic items to use in battle.