Knowledgeability

n.capable, thoughtfulprofessional

What it means

The quality of being well informed and able to use that knowledge.

Reach for it when naming demonstrated command of a subject in formal evaluation

The guide's knowledgeability reassured hikers before the difficult crossing.

everyday
command of the subject
a clear phrase conveys confident understanding
not when Command may sound absolute when the evidence shows solid but incomplete knowledge.
warm
learning
study and intellectual cultivation deserve praise
not when Learning can be theoretical and is less natural as a personal quality count.
professional
competence
the person can perform reliably
not when Competence can come from routine skill without broad subject knowledge.
professional
expertise
deep specialized mastery is well evidenced
not when Expertise claims a higher level than general knowledgeability.
formal
informedness
possession of relevant current facts is what matters
not when Informedness is awkward and says little about applying the information.
literary
erudition
wide scholarly learning is the distinction
not when Erudition sounds academic and may not include practical application.

demonstrated knowledgeability
Demonstrated knowledgeability mattered more than polished presentation.
technical knowledgeability
Her technical knowledgeability helped the panel ask better questions.
guide's knowledgeability
The guide's knowledgeability became clear when the weather changed.

Knowledgeability is valid but awkward; expertise, knowledge, or command of the subject will usually read more naturally.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.