I'll try to provide a literal translation.
Although "Fähigkeit" can be translated as "skill", it's rather an ability.
"Fertigkeit" is a skill.
is used for solid objects or metaphorically for beloved ones.
could be misinterpreted as "to receive", especially when used together with "Fähigkeit".
is unambiguous when used with "Fertigkeit".
plays in the same league (it's one of its synonyms) while shorter, therefore
eine Fertigkeit wahren
For "emotional skills", like humor (mentioned in the comments), use "Wesensart" instead. Additionally I think Matthias' "in Übung bleiben" is a very good choice. It covers all grounds and is more colloquial.