Other rewards that should be mentioned:
1) XP - In the new BGs where you can get XP, kills do not give XP, but completing certain objectives (which differ per battleground) will give you XP. For WSG, you only get XP when your team successfully captures a flag while you are alive. As such, it is always best for the leveling player to attempt to win by capping all three times, not just turtling when you have the lead. It also helps to know when your team is about to cap the flag so that you can do your best to stay alive for the cap - dead toons get no XP. The XP appears to scale with your level (I believe it is 2-3% of a level per flag cap), and does appear to benefit from heirloom bonuses. It does not affect rested XP.

2) More XP and Honor - When leveling, if WSG is the daily BG, you can get more XP and honor by completing that daily. Your faction battlemaster will have the daily quest. There will always be a daily quest available to you, regardless of what the daily would be for a lvl 80. If WSG is the only BG available to you, it will always be the daily. Completing the daily will give you an XP amount that scales with your level, a small amount of silver and bonus honor. With both the heirloom shoulders and chest, you get 10% of a level every time you complete the daily. At low levels, questing is obviously more efficient, but BGs can break up the grind for 20-30 mins at a time.

3) Gear - the biggest complaint about leveling through BGs is that you don't get gear. But if you are questing, have heirloom equipment and doing BGs, you can actually gear yourself pretty well. WSG marks of honor can be turned in (+honor) at the world map location for WSG (North barrens for horde. Don't know where for Allies). There are blue (rare) cloaks and rings, all with a required level that scales with levels that end in 8 (i.e. 28, 38, 48, etc) that are likely to be the best available to you unless you are doing instances regularly. At lvls 40, 50 and 60, for a very reasonable honor cost and the marks, you get an epic set of bracers. The req. lvl 50 bracers can easily last you until you run off to Outland.

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