Revelation 2:26 “And he who overcomes, and keeps My works until the end, to him I will give power over the nations–[27] ‘He shall rule them with a rod of iron; they shall be dashed to pieces like a potter’s vessels’--
The overcoming promise does appear to have a secondary requirement attached apart from merely being an overcomer. The Lord wanted to stress that keeping His works until the end was vital to achieve this particular blessing.