There's a threshold somewhere around 7 weight which, under that, your weight doesn't affect your speed at all. Personally I don't recommend going below the level of lamellar vest unless you're very confident in your blocking and footwork. The lamellar vest is, imo, one of the best body armors for a newer player. It's cheap, gives decent protection, and still barely reduces your speed. I went one gen in tribal armor with an awlpike and a 15/24 build. It was insanely fun, but if I so much as stubbed my toe I lost half my health.
Weapon length DOES reduce your movement speed, not sure by how much, but it isn't really noticeable until you get over around 150 length. I use a pike and with 6 ath and black armor I can still keep up with most people, so while it IS noticeable, it isn't a massive difference.
