There is no such thing as balance in a single player game. The whole term balance, as it relates to video games, came about due to multiplayer.
ofcourse there is
if there's multiple playstyles each should be equally viable to some degree (there's always going to be differences)
if something is so underpowered to the point of become obsolete they did something wrong balance wise
also personally I don't like too much meta gaming
if you have to resort to a certain weapon or style because yours isn't viable or it is the most powerfull
again there's something wrong balance wise
as for this specific matter, haven't really played with 2h weapons since my 2handed stats svck
haven't tried dual wield either
though I never thought about dual enchantments being such a powerful factor (stupid me, kind of obvious)
perhaps I should give it a try sometime
makes me wonder now, if I dual wield a sword and axe and have both perks (decapitation and bleed damage for example) from the 1 handed skill tree will they both work as well?
because that could be a really powerful combination