Silver Los has severe weakness to water and dragon (in that order), but he is very hard headed. Meaning, while most monsters are weak to being hit on the head, this guy will bounce most weapons off it. His body, particularly his back, are susceptible to damage. Instead of going gun-ho to his face, reposition yourself to do as much damage as you can to his back, specially after flashing him in the air.
What this would mean, is that you will be most effective at being in aerial mode and constantly strike his back when he is rushing on the floor. or flash and hit his back otherwise.
When soloing him, almost any blade weapon in aerial will do the trick, but if playing in a group, watergun him, specially if you have paralysis shot. If you can shoot paralysis while he is in the air, he will be vulnerable for an extended period of time. His entire fall/agony animation + the entire duration of the paralysis which only starts at the end of the agony animation.