How can I make a ledge climbable/grabbable?

I've seen this video when a Roblox player is grabbing the ledge. I need to do something like that. I have intermediate Roblox scripting knowledge. I know how to make welds, but I feel welds are not enough. Someone can help me?

You'd be wondering why aren't welds enough, right? This is why:

• The accuracy is important, because a weld fixes the movement of the player, so it might cause glitches to occur.
• Ledge should allow some mobility to the player. Welds prevents user from moving (specially if it's welded to an anchored part), players should be able to move left/right while grabbing the ledge
• If player jumps, he/she should be able to reach the top side of the part that contains the ledge. But welds linked to anchored parts might limit the movement of the player.

I've edited this question to make it 'constructive'