Are you already playing on easy difficulty?
Maybe if you try it again someday, you can build a more effective character before getting the battle tower, so the difficulty afterwards wouldn't be a problem.
The next patch (expected around or before the release of FoV and DKS in October) is changing / adjusting the relatively strong level dependence of combat, so that may make things easier, as well, dealing with level 21 opponents at level 20, etc.
