Well, He’s not “super-fragile”, that was a bit hyperbolic of me to say. I guess the big problem is that he’s not just 5, you also spent 5 on Tech III. Also he can’t patrol at all, so you have this 8 power thing you can use every turn, which is really good, but without Haste you are spending gold and showing your opponent what to do about it. The +1/+1 heroes is decent as well. I like the card, but according to players more experienced than I am, Daigo is not worth the gold.
And yeah, Ninjutsu has redundancy issues. I think the intent is for White to mostly win with its heroes, which is why White heroes have really good ults and their tech IIIs are not the greatest. Fox’s Den Students is much stronger than Jade Fox, and potentially easier to play!