I need validation on all the numeric fields that i’ve got on the grid , now the problem is that onEditCell tries to validate all the columns on the grid irrespective of the cell type, is there any way to validate only numeric columns that are there in the grid.

onEditCell provides the index of column as 3rd parameter, so you can check it and execute validation only for necessary columns.
If numeric columns have some special column type, you can retrieve column type by index as
var type = grid.getColType(index);