Commodity knowledge in respective domain is necessary conditions.
Communication : written and verbal is necessary condition
Strong purchasing process knowledge - RFQ, negotiations, business case, ROI calculation, finalize terms and conditions, do a technical discussion with supplier and engineering.
Costing : Knowledge of costing is must.
Contractualization ; Negotiations with suppliers to sign contract, and ensure performance
Supplier panel : Some long term thinking and supplier assessment.
Negotiations : ability to deal with difficult suppliers to ensure ontime delivery, cost and quality
Must have worked on new supplier additions and supplier base rationalization.