Well I hope they would disarm me! If a sandan lets me get away with an attack without controlling my weapon I would certainly get up for another (due to the nature of the the bokken ukemi as well, if the nage doesn't disarm you there can be the potential for a nasty injury on Nage as you roll, especially if you turn to face them).
Just as a snippet - I heard that there was a problem at one time in Japan due to people doing forward ukemi whilst throwing a dagger behind them (ie. they would throw it between their legs as they did the ukemi). Quite a cool trick, and hard to see coming.