Is there a diety that has trickery in its portfolio and has scimitar as the favored weapon? I'd like to make a LE character that uses dervish dance (VIA dervish of the dawn bard) and makes people think he worships sarenrea.
Martial weapon proficiency is a feat without any prerequisites. Play a human, take that and weapon finesse at first level, and then either wait until level 3 for your next feat. Alternatively, you could play as a half-elf to get the same results through ancestral weapon.
Another alternative which could work with any race is to take a dip into fighter at level 2. That would give you proficiency with all martial weapons and you can take dervish dance with the bonus feat as soon as you have the 2 ranks in dance to take dervish dance.
I am curious how you will deal with the negative energy channeling. You can take care of cure light wounds with prepared spells, but the lack of positive energy might end up being rather noticeable, especially when it seems like it is so effective at lower levels.
Well, Dervish of the Dawn is not going to work for you. It has a religious requirement. And Dervish Dancer is worse, IMO.