I enjoy playing arena. What I enjoy the most is the variety of my team based on the random 3 troop selection. I try to vary my team based on troop mana colors, then I usually choose my Hero weapon based on available mana colors left. The result tends to be a varied party and that's good, keeps the monotony at bay.
1 problem. This is absolutely impossible to do/enjoy when you're constantly facing a Hero with a Runic Blade as an opponent. Especially if you start playing Warlord II or higher, Runic Blade can one shot kill the majority of your troops (then of course it becomes more powerful.) Runic Blade is BY FAR the most common opponent Hero weapon. Based on my experience, when completing an 8-9 match win, Runic Blade will often account for half of the opponent hero weapons, if not more. BORING. Seriously, there are dozens of Hero weapons, some of which I never see in the arena for an opponent. Let's mix it up a little.
I also get it. It's not supposed to be easy, supposed to be very challenging, the Runic Blade makes it very tough for you to achieve 8 wins.
However, there should be balance in place between challenge/diffculty and enjoyment/variety.