The only problem I have with Kilometrico is that the ball has quite a high resistance and hurts my hand when writing essays in exams. 
Agreed, Kilometrico sucks. Extremely high resistance and it runs out sooo quickly.
Hi guys, what is the best pen for writing essays? Like in ancient history we have 3 hours essay writing non-stop!
I would recommend Papermate grip rollerball pen because it is a rollerball(super quick), so much ink flow and extremely quick drying. I am left-handed and these work for me, sure it gets a lot more smudgier than normal but it is doable. Rollerball is sooo good for quick, smooth writing so essays should be no problem and the grip on this pen will help with cramps.
Otherwise, there is the Pilot Dr. Grip Advance ballpoint. It is pretty heavy but it somewhat helps with writing... This IS the smoothest ever pen I have ever used. Minimal smudging because it's a ballpoint and you can refill cartridges which is just a bonus feature. However, a single pen costs you $10.
I have both pens but I prefer the Papermate grip rollerball even though it smudges a lot.
Visiting Officeworks to try out pens is a
must if you need the best pen possible. I have spent probably 2 hours trying pens at the desk they have.