I'll just answer this for future reference, this is coming from a GR30 that have done all quest with end game equipment. No other class comes close to AX Damage, and the 20MP slashing attack is the best melee move in the entire game, short animation so you have little wait for your next move. Other melee class and their 20MP moves are bad in the animation regards. AX's 20MP Strike move is slightly longer but still shorter than most other builds Tier 4 moves. They also have a 2AC strike move that land critical hits, combine this with AX passive ability if you are low HP, you will hit 5K damage often, and even see damage as high as 9K+. From a support standpoint, they have some useful moves. Lower enemies attack and defense, and an inspire all buff, which is helpful because you can no longer learn inspire in the Divine tree in WKC2, and AX is the only build that can do this. They are not good at thrust moves and this is where bow comes in. Hands down the most versatility build in the entire game. Here's a list of things exclusive to their build: 1) The ability to tank bosses, dark shot and agility up (cost 1 ac) is a nasty setup. Which will dodge nearly 100% physical attacks (outside a few special moves that will always hit). WKC2 has plenty of multiple boss fights (mostly comes in trio), so it makes it easier for the entire party if a bow member draws the strongest boss into a corner, while the other members does work on the others. 2) A 50% HP/MP item boost, great for support, or a quick heal in stressful situation. 3) Builds AC nearly twice as fast as other builds, because of their passive ability and short animations. Obviously great for Knights transformation or during tanking. 4) Can always target breakable/vulnerable spots, so it's great for farming or dealing extra damage. 5) MP bow songs (cost 1AC) recover 22% MP of your or an ally MP. The entire Combat system is built around MP, you'll be spamming 20MP moves and it runs out fast in a boss fight, which makes this move extremely useful. 6) They make good healers if you combine this with 1) and 2) ability. Casting Heal 3+ without worrying about being interrupted. For mages, they're known exclusively for three things, shorter casting time than other classes, greats heals HP/infected status, and the best at MP support, has a 3AC move that restores 22% MP from the entire party within range. End game, they offensively struggle, because of bosses resistance to elemental attacks. But I like having at least one in a party because of MP support, any more they can slow the party down.
I have nothing positive to say about SS/LS/Spear because quite frankly, they do have anything remotely close to the overall class skills listed above.
I play a SS/LS currently in WKC, and I am planning on going SS and Bow for part 2. Do these two have any major problems complementing themselves, and after 4 rebirths, is it viable to take axe as a third class with any decent buffs from other trees?
Bow and SS will complement each other fine, you will be losing passive/divine if you try to add another, as the passive from each build takes around 80SP to learn. It's not worth the hassle having three, with the way how armor is interchangeable, it's best to have two weapons in your inventory for switching on the fly.