The round steel buckler is 0 slots, anything over 6 (?) weight is 2.
From what I've read, Shields over 8 weight are 2 slots. I know for a fact it's not 6 weight, cause I have a Kite Shield (6.5 weight) and it only takes 1 slot.
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From what I gather, by your WPF distribution, you plan on melee (sword & board) being your primary, with Crossbow as secondary. Doesn't mean you won't use it a lot. But I take it you are not making a crossbowman who carries a melee weapon. But rather a Shielder who carries a Crossbow.
I'm a Polearm/Thrower Hybrid. I have 3 Shield, and I like my Kite Shield. However, I'm when it comes to melee, I'm using my Polearm, thus I'm not having my shield beat all to hell.
Being a Shielder (melee fighting with a shield), I'd say go with the 5 Shield. It will also allow you to use the Huscarl Shield (2 slots, but seen as one of the best in the game).
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Your inventory layout could look a couple of ways. And with your build, you can mix it up. As you mentioned, you could leave the crossbow out when needed, and situate yourself for a melee battle.
Personally, as a majority, I'd take... 1 One-Handed weapon, 1 (1 slot) shield, the Crossbow, & a bag of bolts.
As mentioned above, you could go with the Round Steel Buckler (0 slot), with the Arbalest crossbow (2 slots), & a bag of bolts. However, the Round Steel Buckler is horrible against enemy ranged. And with it being 7k plus, an the Arbalest 18k plus... you could be looking at an expensive upkeep... especially considering you still have to add in your armor & 1-handed weapon.
For melee, you could take 2 One-Handed weapons & a Huscarl Shield. I really like this layout. The Huscarl is great. And you can bring 2 One-Handed weapons that suit the varying needs on the battlefield. Say an axe for breaking shields and higher damage. Then switch to a sword if you need speed and more reach against an opponent. You really could mix it up here.
Or if you want to be really defensive in melee... you could go with 2 One-Handed weapons and 2 (1 slot) shields. Or even more defensive, just 1 One-Handed weapon, a Huscarl shield, and 1 (1 slot) shield.
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Personally, I think your build above is pretty good. Of course it'd be nice to have more WPF in Crossbow... but at the expense of 1-Handed... you maybe be better off as is (not enough experience with Crossbow to say that 101 WPF will be accurate or inaccurate). And of course it'd be nice to have more PS... but you can't do it all. We'd all love to have 9 PS in every build... or 13 Shield. But you have to give and take with every build. And I think you've found a nice balance with your build.
