Help making an AI less smart for an RPS-like game

Hi all, I'm making an JRPG-type game. It has a turned-based combat system, but instead of taking turns hitting each other, players play essentially a game of rock-paper-scissors-lizard-spock with different payouts for each strategy. I made an AI for this, and it's too smart.

I think what I did is called the "multi-armed bandit" strategy. Basically, I have a bunch of pre-programmed strategies (e.g. always pick strong attacks, always pick weak attacks, pick what would beat what the opponent just played, pick what would beat what I just played, etc). Each turn, it looks at the history, and calculates the expected net payout (damage dealt - damage received) of every strategy. Then, it goes with what ever has the highest net payout. All of the strategies involve picking between 2 of the 5 attacks, so if you know what the computer is going to pick, there is 1 strategy that will beat both. I'm the designer, and it usually beats me.

Do you have thoughts on how to make a dumber-version of my AI, for an "easy mode" of the game? If possible it would be great if it was more deterministic, though I don't need to. (I've thought of cheating 20% of the time and picking something to always loose, but I don't want to go that route)