Shieldbearers are very strong and stubborn Dwarfs - even by Dwarf standards.
They are employed in the personal service of their Dwarf Lord to carry him around on a large shield and act as his bodyguard. This makes their Lord a much tougher warrior on the battlefield and will give him the opportunity, to fight eye to eye with a larger opponent. In fact it allows him, to wield his axe or hammer from a higher position, which makes it much easier to split the skull of a creature larger than a Dwarf like - for example - an Orc, an Elf or an adult human.
One of the most traditionalist Dwarf Lords - Alrik Ranulfsson of Karak Hirn - was the first to be seen carried around by shieldbearers but other Dwarf Lords - and only them - would also make use of this practise soon.
It's reported, that Gotrek Gurnisson, Josef Bugman and Grombrindal apeared during a nearly lost battle in the ruins of Karak Varn, where they safed the day for the Dwarfs. While celebrating the victory they swore, that they would come back and save their dwarfen brothers again, if there would be a real need for. - In this case the three heroes would fight like one and Gotrek and Josef would serve Grombrindal as shieldbearers. Because of the strong and individual character of each dwarf Grombrindal's wisdom of age will not dominate the trio all the time: Sometimes Josef Bugman may decide, that it was time for a little break and a mug of ale to regenerate their energy or Gotrek may run wild because of his unfulfilled slayer oath and start an attack on the mightiest enemy he will find.
- White Dwarf 330 (June 2007), Needs Citation