I've saved the boots of Springheel Jak

[Just Chill]

At the heist (last mission of the thieves guild), you need these boots to survive a long fall.

The effect is scripted for this occasions and that script also destroys the boots (completely removes them from game).

However, that fall can be easily survived with around 50 Acrobatics and 200 Health.
I've had 100 Acrobatics and didn't even lose much health at all.


So best bet would be, if you want to keep boots that fortify Acrobatics by 50 (Acrobatics accepts higher values than 100, even if you cannot level them), don't put the boots on in that quest. ;)