Is there away to make the players weight higher like what SWEP.Weight does but, like ply:SetWeightSpeed?
No. Players have no weight. Nothing in Garry’s Mod is affected by player weight, so I don’t see why you need it.
SWEP.Weight is not what it actually is, it is used solely to decide which weapon is better by the Half-Life 2 weapon system. ( I.E. When you pickup a new gun, if its weight is more then the gun you have currently selected, it will be automatically selected instead, if such option is enabled )