whatever you want, I agree serpent shield looks real good. I actually used the serpent shield in my first play through and found it worked well enough but that was before I learnt how to parry. so if your no good at parrying serpent is good, but once you learn parrying you wont really want to use tower shields anymore.

end game weapons are any of the blackmetal weapons, frostner, drauger fang, porcupine, sledge, crystal axe. silver sword is a good contender for an end game weapon as well fyi