Where does “лоцманский” come from?

лоцманский (Russian) comes from Russian -ский, from Old East Slavic -ьскъ.

Ancestry of “лоцманский”, step by step

Step	Language	Word	Meaning
1	Russian	-ский	Used to form adjectives from nouns or sometimes...
2	Old East Slavic	-ьскъ	—