https://tos-kr.neet.tv/items/124116 6 potential left for upgrade after you max socket it.
https://tos-kr.neet.tv/items/164116
https://tos-kr.neet.tv/items/254118
https://tos-kr.neet.tv/items/274116 - all 3 has 7 potential left for upgrade after you max socket it.
most of 1handed weapons has 7 potential left for upgrade and even more:
https://tos-kr.neet.tv/items/324107 here with 8 potential left for upgrade.
First of all potential/enchant system is already one of the most retarded things in the game, but lets forget about this, just why the hell some weapons has 6 potential for upgrade while other 7 or even 8???