  ARPES mesurements in cuprates have given key information on the temperature
and angle dependence of the gap ($d$-wave order parameter, Fermi arcs and
pseudogap). We show that these features can be understood in terms of a Bose
condensation of interacting {\it pairons} (preformed hole pairs which form in
their local antiferromagnetic environment). Starting from the basic properties
of the pairon wavefunction, we derive the corresponding k-space spectral
function. The latter explains the variation of the ARPES spectra as a function
of temperature and angle up to T*, the onset temperature of pairon formation.
While Bose excitations dominate at the antinode, the fermion excitations
dominate around the nodal direction, giving rise to the Fermi arcs at finite
temperature. This dual role is the key feature distinguishing cuprate from
conventional superconductivity.
