Weapons in Crawl tend to be classed as 'better for the strong' or 'better for the dextrous' in their descriptions. Here is Brent Ross' description of how this works:

Here's some details (not too spoily, it isn't really documented, and
the effect is typically very small):

On a scale of 0-10 (0 being weighted completely to dex, 10 to strength):

    Quick Blade         1
    Whips               2
    Short Blades        2
    Long Swords         3
    Polearms            3       (mostly two-handed so most often == 5)
    Staves              5       (always two-handed (really 3 + 2, see below))
    Axes                6
    Maces/Flails        7
    Giant Clubs         9       (always two-handed (really 7 + 2, see below))

    Unarmed Combat      4 

    Unarmed would have been more dexterity based, but we're being nice
    to trolls and ghouls here (which are strength based fighters who 
    have special benefits to unarmed combat).

    +1 if the weapon is hand-and-a-half and used two-handed
    +2 if the weapon is two-handed

    I mention Giant Clubs (and Giant Spiked) sepearately, because all
    other weapons are capped at 8 (so a Great Mace is 8).  Note that
    this means that two-handed Axes and two-handed Maces are equal with
    regards to this game mechanic.

As for how these weights are applied (currently, this is gets a bit 
spoily... I'll keep the equations out of it):

    - take the interval between strength and dex... and consider the 
      average point:

            |------------------|--------------------|
           STR                AVG                  DEX

    - the effective stat used for to-hit is in the DEX to AVG range
    - the effective stat used for to-dam is in the STR to AVG range

    - the exact value of that effective stat is calculated using
      the above weightings:

      effective to-hit stat = AVG pulled towards DEX by the dex weighting
      effective to-dam stat = AVG pulled towards STR by the str weighting

      (dex weighting = 10 - strength weighting)

      Note: the effective stats are always (STR+DEX)/2 apart, so
      you can imagine it as a slide... at a 10 strength it's on
      STR and AVG, at 0 strength it's at AVG and DEX.

    - the effective stats are used in the same way DEX and STR used
      to be used (which is rather convoluted).  This does mean that
      your high stat is effectively reduced from what it used to be...
      however, the value of your low stat is raised (so a troll with
      a club won't hit for quite as much damage as before, however
      he will probably hit considerably more often and that means 
      he's almost certainly better off than before).

    - Note: if you have strength approximately equal to dexterity
      then you're effectively unrestricted on choice of weapons...
      only those with substanially unbalanced physical stats
      have this as a large consideration (trolls really like
      big clubs, spriggans really love quick blades)... for others
      it might make the effective difference of a few points when
      considering long swords vs maces.  

Brent Ross (bwross@mail.com)