Derived words: pātinu ‘strengthener’ (occ. in personal name only) (CAD P 277); patniš ‘strongly, with strength’ (CAD P 278, AHw. 1582); patnu ‘strong’ (CAD P 278, AHw. 848); pattānu (pattannu) - one who strengthens (occ. in personal names only) (CAD P 284).
No etymology can be suggested.