I think it depends on the enemy faced. Obviously orcs are too big and have too much armour (as well as being immune to knock-backs) for crossbows/impalers to be much use most of the time in melee (although, having said that, they are great for taking out of your pocket to finish them off after a devastating-but-not-quite-fatal swing for your first 6 action points … which also allows the damage bonus from Killing Frenzy to keep going). If the enemy includes several necromancers or goblin shamans or overseers (or even just common ambushers), arming such characters with 3 crossbows/impalers means that they get more attempts to kill the bastards off early (I also give other characters extra crossbows for these battles). I also find 3 crossbows/impalers to be highly effective against raiders, since you can smash their shield with the great-hammer/sword and then impale them with a bolt (+50% damage thanks to Close-Combat Archer) and finish them off (if a comrade hasn’t already done so) on your next turn. Also, if most of the other company members are bearing shields and forming shieldwalls, you can carelessly fire bolts through melee throngs and, if they hit anything, it’ll almost certainly be an enemy …
I had become scornful of the usefulness of the shield skills, but then they added new content and I started looting lots of exotic shields with special attributes, but these precious gems became imperiled against orcs and so I started to see sudden worth in the Deflect perk (and then, with specially protective shields and a large core who all have the ability to form lots of communal shieldwalls while also wearing heavy armour, Shield Expert becomes worthy as well).
I think, for shield builds, it’s best to use the Utility tree first, since that gives you the durability to keep forming shieldwalls while wearing heavy armour, and the tier-1 perks allow you to carry/utilize reserve shields before taking Deflect from the Defence tree. Then you can take any two of Colossus, Battle Forged and Shield Expert, followed by Hold Out, and either Sundering Strikes or the the other tier-1 Defence perk for the final pick (a warhammer in reserve, and/or a special looted sword that’s over 100% effective against armour, probably makes Sundering Strikes not necessary).
Oh, and as for Puncture (and Nimble), I’m planning (before the perk tree is overhauled later this month) to build some nimble “daggermasters” with Defence perks down to Return Favour, and Offence perks including Push the Advantage and Fast Adaptation, and zero Utility perks. The combination of Return Favour, Push the Advantage and Fast Adaptation makes use of the Puncture skill seem mouthwatering …
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