This is their website that explains their fees, but I think it is unclear as to what it means:
http://www.nwa.com/travel/luggage/specialitems.html
Here is what it says for the really lazy:
FIRST PART-
Ski/Snowboard
Two pieces-ski boot bag and one pair of skis are charged the applicable checked bag fee for the 1st or 2nd checked bag. When in excess, each item will be subject to the baggage charge for single piece.
SECOND PART-
Skiing and Snowboarding Equipment
Northwest accepts one ski bag containing skis, poles and bindings and one ski boot bag containing boots as checked baggage - count the two items as one piece of checked baggage. Northwest accepts one item of skiing/snowboarding equipment as one piece of baggage included in the baggage allowance. Ski/snowboard equipment must adhere to normal weight limits. The outside linear dimensions may exceed 80 inches and no oversize baggage fee will apply.
An item of ski equipment is defined as one of the following:
- One (1) ski bag containing up to two (2) pairs of skis and one (1) boot bag
- One (1) snowboard
- One (1) snowboard bag containing up to two (2) snowboards
Additional ski and boot bags will be subject to normal excess charges. Northwest recommends hard-shell cases when checking your ski equipment.
p class="BodyCopy12"> International Travel:- Additional ski and boot bags or equipment that does not fit within the free baggage allowance guidelines will be subject to a rate of $50.00 per bag.
- NOTE: Does not apply to travel within Asia, within Europe, or between Asia and Europe where the piece concept of baggage does not apply, contact Northwest for charges.
Domestic Travel:
- If combined weight of ski bag and boot bag exceed 50 pounds (23 kg) an overweight fee of USD/CAD $50.00 applies.
- Baggage allowance fees apply for each piece of checked ski/snowboard equipment.
