You underestimate yourself. If you are in a fight to the death with an infinate number of 5-year-olds, an normal 5'10", 155 pound man ought to be able to hold his own until complete and total exhaustion. Assuming that they are coming in an uncoordinate mass, as maybe a rate of 10 per minute, I'd think that you could achieve an easy kill rate of that 10-12 per minute and maintain it for several hours. If you are a bigger person, I'd think that you could kill them quickly enough to start to fashion a fortress of dead bodies at some point and maybe get enough rest to last indefinately.
Now, to answer the OP: change my answer above. Instead of "you" it's "1800 lb. bear with razor-freaking-claws" and instead of "5-year-olds" it's "you and your unarmed friends".