Just keep checking the describtion of a skill. If it's limited to its related class it will say so. Otherwise it will just say it's usable by DoW / DoM. Even mage skills can be used on a fighting class. If a certain skill is effective enough for you...well, it's all up to you. Just take what suits your playstyle and see where it gets you. If you don't like a skill on your class, can always replace it with another.
Me's mainly a lancer mixed with marauder and pugilist skills, works out pretty good so far.
Edited, Oct 3rd 2010 5:48am by FanciatheDragonkeeper
FFXI: Rynaria - Mithra on Kujata [retired]
FFXIV: Fancia Dragonkeeper - Miqo'te on Besaid