  The seek of high precision analyses in $\gamma$-ray astronomy leads to the
implementation of multivariate combination, benefiting from several
reconstruction methods. Such analysis, called $X_{eff}$, was developed for the
H.E.S.S. data using three shower reconstruction methods. This paper presents
the improvement granted to this analysis by refining the distribution
calculation of discriminant variables, considering observation conditions, and
adding new variables in the $X_{eff}$ combination. The efficiency of the
analysis is presented using simulations and real data. A comparison with the
standard analysis (model++), for a typical set of sources, shows a significant
gain in sensitivity.
