'less mastery' is correct and usable in written English.
You can use it when talking about a lack of skill or expertise in a particular field or activity. For example: "Although he had studied the subject for years, he still lacked the less mastery required to pass the exam."
"You are translating yourself into a medium over which you have far less mastery," Haeri told me.
IBM's consultants, say rivals, have a fine grasp of the technical issues, but less mastery of the higher-level strategic thinking.
These forms to them appeared "exotic", but they learned to reproduce them with more or less mastery, depending on the extent of their familiarity with the other regions' building traditions.
The "wow" factor is inescapable, yet as one gets deeper into the show, the work becomes less about mastery than about mortality.
Banking profits owe less to mastery of fiendish theories about optimal risk allocation or anything else, and more to an old-fashioned case of what Adam Smith called "a conspiracy against the public".
Levinas again reframes labor, less as mastery and humanization of nature, and more as the creation of a store of goods with which an other can be welcomed.
These findings are broadly consistent with previous research [ 72] that has found worse patient proxy health ratings and less personal mastery to be associated with greater partner (caregiver) depressive symptoms.
He devoted himself to the mastery of single-ball techniques, using an open hand, which allowed for less control and more vulnerability.
Indeed, even as formerly middle-skill occupations are being "deskilled," or stripped of their routine technical tasks (brokering stocks, for example), other formerly high-end occupations are becoming accessible to workers with less esoteric technical mastery (for example, the work of the nurse practitioner, who increasingly diagnoses illness and prescribes drugs in lieu of a physician).
If Mr Trump runs them that day, when the weakness of his campaign's ground game will matter less and his mastery of media communication will count for more, then perhaps no one will be able to slow his march to the party convention in July to accept his crown.
Anything less than perfect mastery, however, and the spectacle degenerated into a tedious, sickening massacre, particularly at the end.
