A welding kit.
Is it an alminum or steel prop (I'll guess aluminum, as steel tends to fold rather than chip.)
Should be repaired by a prop shop that will ensure contour is correct and balance is within limits. (If it's aluminum, and a standard diameter pitch and mount, it may be nearly as cost effective to replace, and hold the old one as an emergency spare.)
An unbalanced prop will accellerate wear on other components, with the propshaft seals being the most concern.
jky
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