Dual wield does not require you to have weapons with different delays, thats
for pets only.

I always tried to wield a different weapon typein my off hand than in my
primary. It helped me keep all 3 skills maxxed. THere is not inherant
advantage in doing this though. If your skills are maxxed (or you don't
care) just wield your two best weapons.

When you initially get dual wield, put your fastest weapon off hand, this
will help your skill go up quickly, but once it is capped (which will take
about a level), go with your two best weapons. At lvl 18 I actually went to
the triple song attack and soloed to 22. (heal song, chords of discord w/
mandolin and DDD with horn)