With this skill, a Gladiator gains an understanding of how his armor can better serve him. Most warriors who wear armor simply allow it to bear the brunt of most blows, relying on the physical barrier to protect them from the dangers of battle. The Gladiator learns to position armor so it absorbs the blow better than it would normally, forcing the heavier parts of the armor to take the main impact of the blow. However, this tends to put a lot of wear and tear on the armor — and if the Gladiator isn't wearing armor, he's bound to get jarred quite a bit.
'put a lot of wear and tear on the armor' means you'll get lot of eq damage, so better get your equipment protected by a friendly merchant (see protect armor).