Depends on how they spin it.
A rod doesn't just have to be a foci on top of a stick.
And if they wanted they could have a dagger in one hand and something else in the off hand.
I feel the answer to your question is yes (hence my previous post). With daggers it might be easier actually because you're right.
And the Necromancer isn't gonna be dancing and zipping about with it's blade like a Ninja does (where as a rod would just casts more magic like how BLM already does. They'd probably look as uniquely stylized as SMN is from SCH lol).
The scythe is def cool and a good idea though, and would most easily have a style all it's own. It's up to them what they'd do with it, but I personally wouldn't write off rods or daggers as possibilities.