Grade Points at the moment I feel like is useless. After getting to Six Paths Sennin I continued to play Arena as much as I liked to, until I couldn't get enough. After a while it got boring, even though this game has a lot of things to do, Arena should be more competitive. Grade Points is an awesome way but there needs to be something else. Arena is missing that spark to be something everyone likes and enjoy. The competitive aspect of it is completely bad. There's nothing besides Arena points and Daily Missions that make players want to play arena to have fun. Some players use it to test teams, and that's a great way to try teams, but there's nothing other than those 3 things I just mentioned that would make Arena any fun for someone who has already gotten to Six Paths. I feel like Arena could be the competitive battling in Naruto Online I know we have Ranked, but that's 3 teams and no balance. Competitive arena could determine the greats. This would be an awesome way to find out where you're at and what would it be like if you have the same amount of power as the person who holds the title "Strong Power". This game would actually bring in more money if that actually happened to be honest. The players who are scared to spend because they don't know if they're going to be good enough to compete would spend if they could go toe to toe with someone strong in arena. Arena doesn't need many things to make it great. These are my suggestions to make it more competitive based and popular.
Arena Rankings. - Other than grade points the real big deal would be "Arena Rankings" like Ranked, you'd have free Arena points coming to you for just having the hard work of keeping and winning back your rank. This would be a W/L ratio with a maximum of 2 wins on the same player every 6 hours or something like that.
Make a Grade Points leaderboard. - People would start playing it to earn more grade points, this would make people want to buy new ninjas and try them out as much as they can. Not to meantion the game will be even more popular since this is something to do for a few people. Maybe the title would be "The Hokage"? I don't know something like that.
Six Paths Sennin continues - Six Paths Sennin is the top rank in Arena you could get at the moment. After this there is nothing else to do in Arena. Maybe making more ranks or even making Star 4 and 5 ext. Would attract more players in to Arena. To get to 5,000 Grade Points it should take you around 225 straight wins, 250 wins if you have around 10-15 losts. 5,000 is not impossible, it's just not worth it.

These are simple ideas, feel free to add any more that would make Arena stand out more, it is such a fun feature, but it's actually not needed after you have Six Paths Sennin and have a team that's good. It's annoying finding players too. I'm from S5 and I have to search 3-10 minutes to find someone on average if it's anytime after 2PM EST when most players dalies are done. Just an idea to bring more fun to everyone playing the game.