"To handle these qualities" refers to the ability or skill to manage or deal with certain characteristics or attributes. It means being able to effectively address and cope with the specific features or traits in question. Full definition
First the poor handling qualities of the suspension were quite noticeable under load. (autolist.com)
• Highly organized, insightful and meticulous individual with over 5 years of experience of handling quality assurance processes, in sync with established protocols. (coverlettersandresume.com)
This includes handling quality control for a national real estate title and escrow firm. (growthequitygroup.com)