Some experience sharing:
Mana. knifes seems good.
However, I can't really find one that gives me a higher dps than the 1h weapon I am currently using.
Since it doesn't have LS/Loh, I still bought a cheap Mana. knife (w/ 3%LS, no socket) to deal with the reflect elites.
It's annoying to switch weapon every time I meet RD., but it doesn't happen not very often (not that many reflects usually).

In this way, I can have a higher DPS most of the time and save me a lot of gold