Tremere guards are well-trained, and know how to fight in groups, with or without a maga.
They're used to face some amount of magic, and know when they're in over their heads.
But that doesn't make them better than any other elite company. There are two things that set them apart. First, the wealth of house Tremere meas they are more likely to be outfitted with Superior equipment, or even Enriched Items. Secondly, and more importantly, they're very brave, and loyal.