Here are my achievements soloing what I could:
WHA/FF = around level 45 I think. Been a long time. I leveled up in the middle of it which was helpful. I never used the Sword of Thorns when I could. So use it as soon as possible.
SVA/A hero is born = soloed it around 115. I used some items for HP or SP from the Jona's quests. It was quite exciting, more so than WHA.
BWA = It has been so long I do not even recall the exact level. It was before level 177, and I used a lot of skill whispers and a lot of miracles so I did not risk the run. It took me many hours as I took my time when running it.
BI = I managed to kill the first bear and a half of another one at level 177 with the use of an anchor before a friend joined me to get rid of the remainder bears. It was not as impressive given the use of an anchor, but it was the first time I could hit the bears a couple of times before they could get rid of me so it was fun nonetheless.
BRA = When I started the run, I was level 199. When I finished it, I was level 201. It took several hours and many skill whispers. This time I did not need to use miracles which was a relief in terms. I kept the chat informed of my progress and while many doubted I could run it to the end, I surprised even myself when I did get to the end of it.
CWA = Level 276 and I missed more defense for some battles as my weapon gave me only help with resistance which was indeed necessary for some of the hardest fights. Death Sword gave me 75 resistance and 0 defense.
Lesson learned, I need more defense when going to CWA or UWA...
UWA = to come, hopefully.
Things changed since I soloed up to BRA, with the availability of stats hats and better weapons, these that are to be gone forever this weekend. So I can see how those stats hats used at level 50 could help a lot at soloing the early arenas and how once folks could get the better weapons they could grind everything to their hearts' content much earlier than I could.
I am a Desert Bandit level 364 and my only skill worth its existance is the Snake Juice II which I have been using all the time I run anything, either to keep me alive or to keep the folks with me alive.
At currently I can heal up to about 8000 HP, 12 times with the standard SP I get. I could always use more Skill Whispers in case of trouble, such as when running UWA in the future.
As a Desert Bandit I also get a considerable hit damage, as the Desert Bandit's attack is above average, which compensates for our lack of defense and resistance along with our improved healing ability. My weapon of choice for now, the Death Sword, is behind other weapons in terms of attack but I still hit hard enough to keep up within distance of the hardest hitters and their sometimes greater attacking weapons. Besides, some of the hardest hitters lack the cool healing ability of the Desert Bandit so we could always help each other.
My suggestion for soloing is Desert Bandit, gold equipments, and Skill Whispers.