Many years ago I saw a set of expansion rules in Dragon or somewhere about a halfling martial art. IIRC the name translated as "Surprise and Smash"
I would tend to have them start with a legsweep or other takedown, then either a killing or NND grab (don't ask where) or maybe a disable element grab. I keep thinking about my 5'4" friend the mixed martial artist, who could take somebody down and cripple them so fast it isn't scary, it is terrifying!
Lots of oportunities, as stated, for "ninja" like tricks. I would think they would be well served by Bolas or lariats, particularly in groups. Maybe the Flying Guillotine.
Blow guns, spears, slings, bows, Stillettos, Bundi,
Very potentially frightening.