In stock form, the Hades has a somewhat uncomfortable vertical foregrip. I don't know why Nerf chose this design, as vertical foregrips are typically reserved for blasters with difficult primes, such as the the Dart Zone Pro line. The stock Hades, however, has an easy prime, so the vertical foregrip is just an annoyance.
This part from OOD solves this completely. It's a real chonky piece of PLA that offers plenty of space for your hand to grip onto and makes the entire experience of using the blaster a much better experience. That being said, it is a LITTLE on the large side, which may be down to Luke having somewhat large hands. For most adults it should be fine, but I could see people with smaller hands having an issue with it.
While I'm extremely fond of the Hades design, I quickly found the stock vertical pump grip required my to stretch my support arm in an awkward way and it really compromised the balance of the blaster. This pump grip changes all that. It brings all-day comfort and a much more natural pumping motion to the table, improving balance and operation. While installation is slightly fiddly with 3 screws at play, once installed it is VERY solid.