Not trully a very important matter, but nen-fighters don't go out with normal weapons around. Better stick to what you have best, and fully trust your abilities, instead of trying to fiddle secret weapons and such tactics.
I believe (shown by other fights) that Nen-user must be confident in their own capacities and chosen weapons. So it kind of goes against the whole ethos of refining nen to use anything else.
Besides, putting Nen on weapons probably takes longer and more aura than just your fist, so it is dangerous, for in a fight you must have to quickly switch focus on body part and whole body. Putting and receding aura from other objects must take more time (if that is not your specialty).
I also think Chrollo want to totally win here, that means using his best personal ability. Spiders have, after all, shown that if you fail that is your fault and lack of skill, so each one must count on themselves. If Chrollo just wanted Hisoka dead, I'm certain the Spiders wouldn't mind offing him all together.
Anyhow, I love this fight. Poor audience... And not knowing Nen it must be all very weird