Proto-Mongolian: *merge-n
Altaic etymology: Altaic etymology
Meaning: sharp-shooter
Russian meaning: хороший стрелок
Written Mongolian: mergen (L 537)
Middle Mongolian: mergan (HY 37, SH)
Khalkha: mergen
Buriat: merge(n)
Kalmuck: mergṇ
Ordos: mergen
Dongxian: merɣen (Тод. Дн.)
Dagur: mergen (Тод. Даг. 154), meregen (MD 190)
Monguor: mergen (SM 236), murgen
Comments: KW 261-262, MGCD 485. A later semantic development is 'sharp-shooter' > 'skilled, wise', although Doerfer (TMN 1, 498) suggests rather 'skilled' > 'skilled in shooting'. If he is correct, the Mong. word should be removed from the Altaic etymology. In any case, Mong. > Manchu mergen 'a very good hunter or fisherman; outstanding, wise, worthy, skilled', Evk. mergen 'mind, reason' etc. (see ТМС 1, 571, Doerfer MT 80,Rozycki 158),
Вы совершенно правы, и это тоже монголизм