i think that it is quite old and it will not receive any technical support from apple anymore.
you should give more detail related to it whether is jail breaked or not.
Well yes, it is a second hand phone and anything you might buy upto 5C would probably not have a warranty on it. It isn't jail broken.
what are the issues it is having,is it in perfect condition,i am willing to purchase it ,just pm me the location and mode of payment.