When did Nexon add this?

That is true. The higher your "hands", it's less likely you'll fall off of a ladder/rope when hit.

Hands was added WAYYYYYYY before maker. So it probably doesn't have ANYTHING to do with it.

First part: No. Lol. What affects if you stay on a ladder is if the monster is using a snipe effect magic skill (I.E., Newts with their magic blast, or the infamous Master Chronos spamming their magics at CPQ 5/6). If you hold up to regular things, you won't get kb'd off. If you're standing still, anything will knock you off. Hands to hold on a rope is a disproven rumor.

ON the other hand:

The higher your Hands stat is (OMFG HANDS IS USED FOR SOMETHING), the lower the failure rate is, but this doesn't lower the odds of the item coming out below.

Hm? It's used for maker.