1) Mechanical hand tool 
A putty knife is a specialized tool used when glazing single glazed windows, to work putty around the edges of each pane of glass. An experienced glazer will apply the putty by hand, and then smooth it with the knife. Modern insulated glazing may use other ways of securing the glass to the window frame. A spackle knife (called a scraper in British...
[n] - a spatula used to mix or apply putty
noun a spatula used to mix or apply putty
a tool for puttying, having a broad flexible blade.