There is a bewildering array of close combat weapons ranging from simple clubs and axes to hand flamers and chainswords.
These weapons confer no bonus to the Strength or hitting power of combatants. However, as a model with a weapon in each hand gains an additional Attack against an enemy in base-to-base contact, swords and pistols (or similar hand weapons) remain a useful combination for hand-to-hand fighting. A plasma pistol, like other pistols, can be used as a close combat weapon. It confers no Strength bonus or particular armour penetration advantages though.