Etz'nab', the flint, is eighteenth of the twenty, following Kab'an the earth: after the earth has moved, the cut. Its glyph is a flint or obsidian blade — the Maya made weapons, surgery and sacrifice with it, and polished obsidian into mirrors for divination. So Etz'nab' is at once blade and mirror: cutting true from false, showing what's there.
So Etz'nab''s mechanism is discernment and severance: one stroke, and the cut face is clean. Its power is clarity — you can tell what's real; its difficulty is slack — some relationships, some stages, need not clarity but not-yet.
Where you'll recognise it: sensitive to falseness, direct in speech, able to name the point in one sentence amid chaos, unable to bear fudging, and the occasional discovery afterward that you cut too fast. Running well, you're the most honest mirror: letting people see what's so, separating what was tangled, making the call others daren't. Stuck, you wound or go cold — cutting for the sake of it, honesty used as licence not to be gentle, and finding after the cut that you're on the far side of it too. In the sequence Etz'nab' is followed by Kawak, the storm: after the cut, release and cleansing. Your next step isn't another cut. It's giving what's already cut time to grow back.